ARM: imx: imx8m: env: Switch to arch_env_get_location()

Implement arch_env_get_location() instead of env_get_location(), so that
the env_get_location() can be implemented on board level and override the
arch_env_get_location() architecture defaults.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Adam Ford <aford173@gmail.com>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Marek BehĂșn <marek.behun@nic.cz>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Tim Harvey <tharvey@gateworks.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Tommaso Merciai <tomm.merciai@gmail.com>
Cc: Vladimir Oltean <vladimir.oltean@nxp.com>
diff --git a/arch/arm/mach-imx/imx8m/soc.c b/arch/arm/mach-imx/imx8m/soc.c
index 8171631..7059d87 100644
--- a/arch/arm/mach-imx/imx8m/soc.c
+++ b/arch/arm/mach-imx/imx8m/soc.c
@@ -1528,7 +1528,7 @@
 #endif
 
 #if defined(CONFIG_IMX8MN) || defined(CONFIG_IMX8MP)
-enum env_location env_get_location(enum env_operation op, int prio)
+enum env_location arch_env_get_location(enum env_operation op, int prio)
 {
 	enum boot_device dev = get_boot_device();