cmd: pmic: annotate switch/case fallthrough

The argument parsing code in the pmic command uses an implicit switch/case
fallthrough to handle the common part of having one or two arguments.

Add our "fallthrough;" statement-like macro before the second branch in
the parsing code, to avoid a warning when GCC's -Wimplicit-fallthrough
warning option is enabled.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

cmd/pmic.c

@@ -34,6 +34,7 @@ static int do_dev(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 			printf("Can't get PMIC: %s!\n", name);
 			return failure(ret);
 		}
+		fallthrough;
 	case 1:
 		if (!currdev) {
 			printf("PMIC device is not set!\n\n");