configs: Migrate CONFIG_NR_DRAM_BANKS

We have the following cases:
- CONFIG_NR_DRAM_BANKS was defined, migrate normally
- CONFIG_NR_DRAM_BANKS_MAX was defined and then used for
  CONFIG_NR_DRAM_BANKS after a check, just migrate it over now.
- CONFIG_NR_DRAM_BANKS was very oddly defined on p2771-0000-* (to 1024 +
  2), set this to 8.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am57xx_evm_defconfig b/configs/am57xx_evm_defconfig
index 52e5d6b..229b7e5 100644
--- a/configs/am57xx_evm_defconfig
+++ b/configs/am57xx_evm_defconfig
@@ -10,6 +10,7 @@
 CONFIG_ARMV7_LPAE=y
 CONFIG_DEFAULT_DEVICE_TREE="am572x-idk"
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_NR_DRAM_BANKS=2
 CONFIG_SPL_LOAD_FIT=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_USE_BOOTARGS=y