MTD: Fix bug in fixup_convert_atmel_pri

The memset() in fixup_convert_atmel_pri is supposed to zero out
everything except the first 5 bytes in *extp, but it ends up zeroing
out something way outside the struct instead. Fix this potentially
dangerous code by casting the pointer to char * before doing
arithmetic.
Signed-off-by: Håvard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/chips/cfi_cmdset_0002.c

@@ -175,7 +175,7 @@ static void fixup_convert_atmel_pri(struct mtd_info *mtd, void *param)
 	struct cfi_pri_atmel atmel_pri;
 
 	memcpy(&atmel_pri, extp, sizeof(atmel_pri));
-	memset(extp + 5, 0, sizeof(*extp) - 5);
+	memset((char *)extp + 5, 0, sizeof(*extp) - 5);
 
 	if (atmel_pri.Features & 0x02)
 		extp->EraseSuspend = 2;