cmd: pinmux: Add pinmux command

pinmux command allows to :
 - list all pin-controllers available on platforms
 - select a pin-controller
 - display the muxing of all pins of the current pin-controller
   or all pin-controllers depending of given options

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
cmd: pinmux: Fix pinmux command

if "pinmux status" command is used without having
set dev using "pinmux dev", print pinmux usage
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index d609f9d..e2973b3 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -953,6 +953,14 @@
 	  about 1990. These devices are typically removable memory or network
 	  cards using a standard 68-pin connector.
 
+config CMD_PINMUX
+	bool "pinmux - show pins muxing"
+	default y if PINCTRL
+	help
+	  Parse all available pin-controllers and show pins muxing. This
+	  is useful for debug purpoer to check the pin muxing and to know if
+	  a pin is configured as a GPIO or as an alternate function.
+
 config CMD_POWEROFF
 	bool "poweroff"
 	help