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>
diff --git a/cmd/pmic.c b/cmd/pmic.c
index 3ad1b8a..e5fc8f9 100644
--- a/cmd/pmic.c
+++ b/cmd/pmic.c
@@ -34,6 +34,7 @@
 			printf("Can't get PMIC: %s!\n", name);
 			return failure(ret);
 		}
+		fallthrough;
 	case 1:
 		if (!currdev) {
 			printf("PMIC device is not set!\n\n");