imx: imx8mm_evk: remove hdmi fw info from README

The imx8mm doesn't require the hdmi firmware.
Update also the fw version.

Signed-off-by: Flavio Suligoi <f.suligoi@asem.it>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/board/freescale/imx8mm_evk/README b/board/freescale/imx8mm_evk/README
index c908c0a..9921b35 100644
--- a/board/freescale/imx8mm_evk/README
+++ b/board/freescale/imx8mm_evk/README
@@ -15,12 +15,12 @@
 $ make PLAT=imx8mm bl31
 $ cp build/imx8mm/release/bl31.bin $(builddir)
 
-Get the ddr and hdmi firmware
+Get the ddr firmware
 =============================
 $ wget https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/firmware-imx-8.0.bin
 $ chmod +x firmware-imx-8.0.bin
 $ ./firmware-imx-8.0
-$ cp firmware-imx-7.9/firmware/ddr/synopsys/lpddr4*.bin $(builddir)
+$ cp firmware-imx-8.0/firmware/ddr/synopsys/lpddr4*.bin $(builddir)
 
 Build U-Boot
 ============