imx: Suggest the NXP ATF github repo

As explained in the text at the bottom of the page
https://source.codeaurora.org/external/imx/imx-atf:

"QUIC repositories on this site will not receive any updates after
March 31, 2022, and will be deleted on March 31, 2023."

Point to the NXP ATF github repo instead.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Oliver Graute <oliver.graute@kococonnector.com>
Reviewed-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
diff --git a/board/beacon/imx8mm/README b/board/beacon/imx8mm/README
index c65acef..32b24bc 100644
--- a/board/beacon/imx8mm/README
+++ b/board/beacon/imx8mm/README
@@ -11,7 +11,7 @@
 ======================================
 Note: $(srctree) is U-Boot source directory
 
-$ git clone https://source.codeaurora.org/external/imx/imx-atf
+$ git clone https://github.com/nxp-imx/imx-atf
 $ git lf-5.10.72-2.2.0
 $ make PLAT=imx8mm bl31 CROSS_COMPILE=aarch64-linux-gnu-
 $ cp build/imx8mm/release/bl31.bin $(srctree)
diff --git a/board/beacon/imx8mn/README b/board/beacon/imx8mn/README
index 788ab10..49da03c 100644
--- a/board/beacon/imx8mn/README
+++ b/board/beacon/imx8mn/README
@@ -11,7 +11,7 @@
 ======================================
 Note: $(srctree) is U-Boot source directory
 
-$ git clone https://source.codeaurora.org/external/imx/imx-atf
+$ git clone https://github.com/nxp-imx/imx-atf
 $ git lf-5.10.72-2.2.0
 $ make PLAT=imx8mn bl31 CROSS_COMPILE=aarch64-linux-gnu-
 $ cp build/imx8mn/release/bl31.bin $(srctree)
diff --git a/board/freescale/imx8qm_mek/README b/board/freescale/imx8qm_mek/README
index b1a4c6c..47fae3d 100644
--- a/board/freescale/imx8qm_mek/README
+++ b/board/freescale/imx8qm_mek/README
@@ -12,7 +12,7 @@
 Get and Build the ARM Trusted firmware
 ======================================
 
-$ git clone https://source.codeaurora.org/external/imx/imx-atf
+$ git clone https://github.com/nxp-imx/imx-atf
 $ cd imx-atf/
 $ git checkout origin/imx_4.14.78_1.0.0_ga -b imx_4.14.78_1.0.0_ga
 $ make PLAT=imx8qm bl31
diff --git a/board/gateworks/venice/README b/board/gateworks/venice/README
index 9f3a250..ea9b834 100644
--- a/board/gateworks/venice/README
+++ b/board/gateworks/venice/README
@@ -10,7 +10,7 @@
 
 Get and Build the ARM Trusted firmware
 ======================================
-$ git clone https://source.codeaurora.org/external/imx/imx-atf
+$ git clone https://github.com/nxp-imx/imx-atf
 $ git checkout imx_5.4.47_2.2.0
 $ make PLAT=imx8mm CROSS_COMPILE=aarch64-linux-gnu- bl31
 $ cp build/imx8mm/release/bl31.bin .
diff --git a/board/google/imx8mq_phanbell/README b/board/google/imx8mq_phanbell/README
index 88a136b..7c63fc5 100644
--- a/board/google/imx8mq_phanbell/README
+++ b/board/google/imx8mq_phanbell/README
@@ -10,7 +10,7 @@
 Get and Build the ARM Trusted firmware
 ======================================
 Note: srctree is U-Boot source directory
-Get ATF from: https://source.codeaurora.org/external/imx/imx-atf
+Get ATF from: https://github.com/nxp-imx/imx-atf
 branch: imx_4.19.35_1.0.0
 $ make PLAT=imx8mq bl31
 $ cp build/imx8mq/release/bl31.bin $(builddir)
diff --git a/board/ronetix/imx8mq-cm/README b/board/ronetix/imx8mq-cm/README
index 1d43fa5..c57ff24 100644
--- a/board/ronetix/imx8mq-cm/README
+++ b/board/ronetix/imx8mq-cm/README
@@ -9,7 +9,7 @@
 
 Get and Build the ARM Trusted firmware
 ======================================
-$ git clone https://source.codeaurora.org/external/imx/imx-atf
+$ git clone https://github.com/nxp-imx/imx-atf
 $ cd imx-atf
 $ git checkout imx_4.19.35_1.0.0
 $ make PLAT=imx8mq bl31