mtd: fix false positive "Offset exceeds device limit" error

Since commit 09c3280754f8 (mtd, nand: Move common functions from
cmd_nand.c to common place), NAND commands would not work at all
on large devices.

    => nand read 80000000 10000 10000

    NAND read: Offset exceeds device limit
    => nand erase 100000 100000

    NAND erase: Offset exceeds device limit

The type of the "size" of "struct mtd_info" is uint64_t, while
mtd_arg_off_size() and mtd_arg_off() treat chipsize as int type.
The chipsize is wrapped around if the argument is given with 2GB
or larger.

Acked-by: Heiko Schocher <hs@denx.de>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/mtd/mtd_uboot.c b/drivers/mtd/mtd_uboot.c
index 7197007..c517b9c 100644
--- a/drivers/mtd/mtd_uboot.c
+++ b/drivers/mtd/mtd_uboot.c
@@ -43,7 +43,7 @@
 }
 
 int mtd_arg_off(const char *arg, int *idx, loff_t *off, loff_t *size,
-		loff_t *maxsize, int devtype, int chipsize)
+		loff_t *maxsize, int devtype, uint64_t chipsize)
 {
 	if (!str2off(arg, off))
 		return get_part(arg, idx, off, size, maxsize, devtype);
@@ -59,7 +59,8 @@
 }
 
 int mtd_arg_off_size(int argc, char *const argv[], int *idx, loff_t *off,
-		 loff_t *size, loff_t *maxsize, int devtype, int chipsize)
+		     loff_t *size, loff_t *maxsize, int devtype,
+		     uint64_t chipsize)
 {
 	int ret;