cmd: add ADC cli commands

Add an 'adc' cli command to get information from adc devices and to read
"single shot" data.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index ae49b82..eb14e08 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -601,6 +601,14 @@
 	help
 	  ARM Ltd reference designs flash partition access
 
+config CMD_ADC
+	bool "adc - Access Analog to Digital Converters info and data"
+	select ADC
+	select DM_REGULATOR
+	help
+	  Shows ADC device info and permit printing one-shot analog converted
+	  data from a named Analog to Digital Converter.
+
 config CMD_CLK
 	bool "clk - Show clock frequencies"
 	help