cfi_flash: return NULL for invalid base address input

When base address given was out of valid flash address ranges,
flash_get_info() function returned the pointer to the last
element of flash_info[i] array.

This patch changes this function to return NULL pointer
in such a case, which is more correct behaviour.

The function flash_protect_default() calls flash_protect()
immediately after flash_get_info() invocation.
With this correction, flash_protect() function would be
able to return soon, for NULL flash_info.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c
index 28250c2..25f8752 100644
--- a/drivers/mtd/cfi_flash.c
+++ b/drivers/mtd/cfi_flash.c
@@ -184,16 +184,16 @@
 flash_info_t *flash_get_info(ulong base)
 {
 	int i;
-	flash_info_t *info = NULL;
+	flash_info_t *info;
 
 	for (i = 0; i < CONFIG_SYS_MAX_FLASH_BANKS; i++) {
 		info = &flash_info[i];
 		if (info->size && info->start[0] <= base &&
 		    base <= info->start[0] + info->size - 1)
-			break;
+			return info;
 	}
 
-	return info;
+	return NULL;
 }
 #endif