[PATCH V2] cmd: mmc: update the mmc command's usage about argument

[Jaehoon Chung]

It's confusing whether arguments are optional or mandatory.
Update the command's usage to clarify how to use.

Signed-off-by: Jaehoon Chung <jh80.chung at samsung.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
---
Changed on V2
- Update commit-msg
- Add Simon's Reviewed-by tag
---
 cmd/mmc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cmd/mmc.c b/cmd/mmc.c
index 1529a3e05ddd..cb6b59f36a43 100644
--- a/cmd/mmc.c
+++ b/cmd/mmc.c
@@ -1017,13 +1017,13 @@ U_BOOT_CMD(
 	"  Power cycling is required to initialize partitions after set to complete.\n"
 #endif
 #ifdef CONFIG_SUPPORT_EMMC_BOOT
-	"mmc bootbus dev boot_bus_width reset_boot_bus_width boot_mode\n"
+	"mmc bootbus <dev> <boot_bus_width> <reset_boot_bus_width> <boot_mode>\n"
 	" - Set the BOOT_BUS_WIDTH field of the specified device\n"
 	"mmc bootpart-resize <dev> <boot part size MB> <RPMB part size MB>\n"
 	" - Change sizes of boot and RPMB partitions of specified device\n"
-	"mmc partconf dev [boot_ack boot_partition partition_access]\n"
+	"mmc partconf <dev> [boot_ack boot_partition partition_access]\n"
 	" - Show or change the bits of the PARTITION_CONFIG field of the specified device\n"
-	"mmc rst-function dev value\n"
+	"mmc rst-function <dev> <value>\n"
 	" - Change the RST_n_FUNCTION field of the specified device\n"
 	"   WARNING: This is a write-once field and 0 / 1 / 2 are the only valid values.\n"
 #endif
-- 
2.29.0