cmd: pinmux: depend on PINCTRL

The pinmux command uses functions pinctrl_get_pin_*(), which are missing
if PINCTRL config option is disabled.

Signed-off-by: Marek BehĂșn <marek.behun@nic.cz>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 928a2a0..4defbd9 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1188,6 +1188,7 @@
 
 config CMD_PINMUX
 	bool "pinmux - show pins muxing"
+	depends on PINCTRL
 	default y if PINCTRL
 	help
 	  Parse all available pin-controllers and show pins muxing. This