riscv: qemu: Enable MTD NOR flash support

Enable support to the 2 NOR flashes on the QEMU RISC-V virt machine.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/include/configs/qemu-riscv.h b/include/configs/qemu-riscv.h
index 5291de8..bbeea96 100644
--- a/include/configs/qemu-riscv.h
+++ b/include/configs/qemu-riscv.h
@@ -29,6 +29,8 @@
 
 #define CONFIG_STANDALONE_LOAD_ADDR	0x80200000
 
+#define CONFIG_SYS_MAX_FLASH_BANKS	2
+
 #define RISCV_MMODE_TIMERBASE		0x2000000
 #define RISCV_MMODE_TIMER_FREQ		1000000