common/cmd_nand.c: Fix GCC 4.6 warning

cmd_nand.c: In function 'raw_access':
cmd_nand.c:397:9: warning: variable 'rwsize' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: Scott Wood <scottwood@freescale.com>
diff --git a/common/cmd_nand.c b/common/cmd_nand.c
index f060a31..fa44295 100644
--- a/common/cmd_nand.c
+++ b/common/cmd_nand.c
@@ -394,7 +394,6 @@
 			int read)
 {
 	int ret = 0;
-	size_t rwsize;
 
 	while (count--) {
 		/* Raw access */
@@ -406,7 +405,6 @@
 			.mode = MTD_OOB_RAW
 		};
 
-		rwsize = nand->writesize + nand->oobsize;
 		if (read)
 			ret = nand->read_oob(nand, off, &ops);
 		else