cmd_nand: Update (nand_info_t*)nand after arg_off(_size) call

The arg_off() and arg_off_size() update the 'current NAND
device' variable (dev). This is then used when assigning the
(nand_info_t*)nand value. Place the assignment after the
arg_off(_size) calls to prevent using incorrect (nand_info_t*)
nand value.

Signed-off-by: Rostislav Lisovy <lisovy@merica.cz>
diff --git a/common/cmd_nand.c b/common/cmd_nand.c
index f9ced9d..7f962dc 100644
--- a/common/cmd_nand.c
+++ b/common/cmd_nand.c
@@ -647,8 +647,6 @@
 		read = strncmp(cmd, "read", 4) == 0; /* 1 = read, 0 = write */
 		printf("\nNAND %s: ", read ? "read" : "write");
 
-		nand = &nand_info[dev];
-
 		s = strchr(cmd, '.');
 
 		if (s && !strcmp(s, ".raw")) {
@@ -657,6 +655,8 @@
 			if (arg_off(argv[3], &dev, &off, &size, &maxsize))
 				return 1;
 
+			nand = &nand_info[dev];
+
 			if (argc > 4 && !str2long(argv[4], &pagecount)) {
 				printf("'%s' is not a number\n", argv[4]);
 				return 1;
@@ -679,6 +679,8 @@
 			rwsize = size;
 		}
 
+		nand = &nand_info[dev];
+
 		if (!s || !strcmp(s, ".jffs2") ||
 		    !strcmp(s, ".e") || !strcmp(s, ".i")) {
 			if (read)