rockchip: rk3288-evb: update CONFIG_NR_DRAM_BANKS to 2

The OPTEE will use the ram start at 0x8400000 which make the DRAM be two
banks.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/configs/evb-rk3288_defconfig b/configs/evb-rk3288_defconfig
index 4b90463..82b5e4e 100644
--- a/configs/evb-rk3288_defconfig
+++ b/configs/evb-rk3288_defconfig
@@ -5,7 +5,7 @@
 CONFIG_TARGET_EVB_RK3288=y
 CONFIG_ENV_OFFSET=0x3F8000
 CONFIG_SPL_STACK_R_ADDR=0x04000000
-CONFIG_NR_DRAM_BANKS=1
+CONFIG_NR_DRAM_BANKS=2
 CONFIG_SPL_SIZE_LIMIT=0x4b000
 CONFIG_DEBUG_UART_BASE=0xff690000
 CONFIG_DEBUG_UART_CLOCK=24000000