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/bg0900_defconfig b/configs/bg0900_defconfig
index fa8f6dc..b30da0c 100644
--- a/configs/bg0900_defconfig
+++ b/configs/bg0900_defconfig
@@ -7,6 +7,7 @@
 CONFIG_TARGET_BG0900=y
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_SPL=y
+CONFIG_NR_DRAM_BANKS=1
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyAMA0,115200"