imx8m*_venice: move venice to OF_UPSTREAM

Move to imx8m{m,n,p}-venice to OF_UPSTREAM:
 - replace the non-upstream generic imx8m{m,n,p}-venice dt with one of the
   dt's from the OF_LIST
 - handle the fact that dtbs now have a 'freescale/' prefix
 - imply OF_UPSTREAM
 - remove rudundant files from arch/arm/dts leaving only the
   *-u-boot.dtsi files

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
diff --git a/arch/arm/mach-imx/imx8m/Kconfig b/arch/arm/mach-imx/imx8m/Kconfig
index 328c3e3..5db643c 100644
--- a/arch/arm/mach-imx/imx8m/Kconfig
+++ b/arch/arm/mach-imx/imx8m/Kconfig
@@ -119,6 +119,7 @@
 	select FSL_CAAM
 	select ARCH_MISC_INIT
 	select SPL_CRYPTO if SPL
+	imply OF_UPSTREAM
 
 config TARGET_KONTRON_MX8MM
 	bool "Kontron Electronics N80xx"
@@ -167,6 +168,7 @@
 	select FSL_CAAM
 	select ARCH_MISC_INIT
 	select SPL_CRYPTO if SPL
+	imply OF_UPSTREAM
 
 config TARGET_IMX8MP_DATA_MODUL_EDM_SBC
 	bool "Data Modul eDM SBC i.MX8M Plus"
@@ -227,6 +229,7 @@
 	select FSL_CAAM
 	select ARCH_MISC_INIT
 	select SPL_CRYPTO if SPL
+	imply OF_UPSTREAM
 
 config TARGET_PICO_IMX8MQ
 	bool "Support Technexion Pico iMX8MQ"