board: ti: am57xx: Add dt support for BeagleBoard-X15 revC

Add support for selecting proper dtb for
am57xx BeagleBoard X15 revC u-boot from FIT

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am57xx_evm_defconfig b/configs/am57xx_evm_defconfig
index 3d455eb..0e4679a 100644
--- a/configs/am57xx_evm_defconfig
+++ b/configs/am57xx_evm_defconfig
@@ -39,7 +39,7 @@
 CONFIG_ISO_PARTITION=y
 CONFIG_OF_CONTROL=y
 CONFIG_SPL_OF_CONTROL=y
-CONFIG_OF_LIST="am57xx-beagle-x15 am57xx-beagle-x15-revb1 am572x-idk am571x-idk"
+CONFIG_OF_LIST="am57xx-beagle-x15 am57xx-beagle-x15-revb1 am57xx-beagle-x15-revc am572x-idk am571x-idk"
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_DM=y
 CONFIG_SPL_DM=y