arm: dts: iot2050: Add support for M.2 variant

Add support for the M.2 board based on the iot2050 advanced board.
The board has two m.2 connectors, one is B-keyed, the other E-keyed.
The B-key slot can connect 5G/SSD devices, and E-key can be used for
WIFI/BT devices.

This variant is covered by PG2 firmware image.

Signed-off-by: chao zeng <chao.zeng@siemens.com>
[Jan: align DT to kernel, polish wording]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index c160e884..79ed4ac 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -1259,7 +1259,8 @@
 	k3-am6528-iot2050-basic.dtb \
 	k3-am6528-iot2050-basic-pg2.dtb \
 	k3-am6548-iot2050-advanced.dtb \
-	k3-am6548-iot2050-advanced-pg2.dtb
+	k3-am6548-iot2050-advanced-pg2.dtb \
+	k3-am6548-iot2050-advanced-m2.dtb
 dtb-$(CONFIG_SOC_K3_J721E) += k3-j721e-common-proc-board.dtb \
 			      k3-j721e-r5-common-proc-board.dtb \
 			      k3-j7200-common-proc-board.dtb \