cmd_part: don't print cmd name twice in help

The core implementation of "help" already prints the command name before
the help text of a specific command. Remove it from part's own help text
to avoid it being printed twice:

Tegra114 (Dalmore) # help part
part - disk partition related commands

Usage:
part part uuid <interface> <dev>:<part>
    - print partition UUID
...

Signed-off-by: Stephen Warren <swarren@nvidia.com>

common/cmd_part.c

@@ -96,7 +96,7 @@ int do_part(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 U_BOOT_CMD(
 	part,	5,	1,	do_part,
 	"disk partition related commands",
-	"part uuid <interface> <dev>:<part>\n"
+	"uuid <interface> <dev>:<part>\n"
 	"    - print partition UUID\n"
 	"part uuid <interface> <dev>:<part> <varname>\n"
 	"    - set environment variable to partition UUID\n"