cmd_mmc: fix bootpart-resize maxarg to 4

sub-command 'bootpart-resize' check for argc == 4,
it will retrun CMD_RET_FAILURE when argc value not matched.

but bootpart-resize's maxarg is 3, which means you never execute
this sub-command successfully.

fix it by change bootpart-resize maxarg to 4.

Signed-off-by: wally.yeh <wally.yeh@atrustcorp.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Pierre Aubert <p.aubert@staubli.com>
Acked-by: Pantelis Antoniou <panto@antoniou-consulting.com>

common/cmd_mmc.c

@@ -602,7 +602,7 @@ static cmd_tbl_t cmd_mmc[] = {
 	U_BOOT_CMD_MKENT(list, 1, 1, do_mmc_list, "", ""),
 #ifdef CONFIG_SUPPORT_EMMC_BOOT
 	U_BOOT_CMD_MKENT(bootbus, 5, 0, do_mmc_bootbus, "", ""),
-	U_BOOT_CMD_MKENT(bootpart-resize, 3, 0, do_mmc_boot_resize, "", ""),
+	U_BOOT_CMD_MKENT(bootpart-resize, 4, 0, do_mmc_boot_resize, "", ""),
 	U_BOOT_CMD_MKENT(partconf, 5, 0, do_mmc_partconf, "", ""),
 	U_BOOT_CMD_MKENT(rst-function, 3, 0, do_mmc_rst_func, "", ""),
 #endif