cmd: pmic: update help description

Change help description to match the style of the other U-Boot commands
and get rid of the leading whitespace.

Signed-off-by: Klaus Goger <klaus.goger@theobroma-systems.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>

cmd/pmic.c

@@ -201,7 +201,7 @@ static int do_pmic(cmd_tbl_t *cmdtp, int flag, int argc,
 }
 
 U_BOOT_CMD(pmic, CONFIG_SYS_MAXARGS, 1, do_pmic,
-	" operations",
+	"PMIC sub-system",
 	"list          - list pmic devices\n"
 	"pmic dev [name]    - show or [set] operating PMIC device\n"
 	"pmic dump          - dump registers\n"