include: configs: Update env for selecting right dtb

Now that single defconfig can be used for booting AM64 EVM and SK,
default device tree will not work for selecting dtb for kernel.
Update the env to select right dtb based on eeprom.
Signed-off-by: NLokesh Vutla <lokeshvutla@ti.com>

include/configs/am64x_evm.h

@@ -58,10 +58,13 @@
 
 /* U-Boot general configuration */
 #define EXTRA_ENV_AM642_BOARD_SETTINGS					\
-	"default_device_tree=" CONFIG_DEFAULT_DEVICE_TREE ".dtb\0"	\
 	"findfdt="							\
-		"setenv name_fdt ${default_device_tree};"		\
-		"setenv fdtfile ${name_fdt}\0"				\
+		"if test $board_name = am64x_gpevm; then " \
+			"setenv fdtfile k3-am642-evm.dtb; fi; " \
+		"if test $board_name = am64x_skevm; then " \
+			"setenv fdtfile k3-am642-sk.dtb; fi;" \
+		"if test $fdtfile = undefined; then " \
+			"echo WARNING: Could not determine device tree to use; fi; \0" \
 	"name_kern=Image\0"						\
 	"console=ttyS2,115200n8\0"					\
 	"args_all=setenv optargs earlycon=ns16550a,mmio32,0x02800000 "	\
@@ -76,7 +79,7 @@
 	"bootdir=/boot\0"						\
 	"rd_spec=-\0"							\
 	"init_mmc=run args_all args_mmc\0"				\
-	"get_fdt_mmc=load mmc ${bootpart} ${fdtaddr} ${bootdir}/${name_fdt}\0" \
+	"get_fdt_mmc=load mmc ${bootpart} ${fdtaddr} ${bootdir}/${fdtfile}\0" \
 	"get_overlay_mmc="						\
 		"fdt address ${fdtaddr};"				\
 		"fdt resize 0x100000;"					\