drivers: hierarchize drivers Kconfig menu

The menuconfig for drivers are getting more and more cluttered
and unreadable because too many entries are displayed in a single
flat menu.  Use hierarchic menu for each category.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Update to apply again in a few places, drop USB hunk]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/sound/Kconfig b/drivers/sound/Kconfig
index 3b96e84..5de86c0 100644
--- a/drivers/sound/Kconfig
+++ b/drivers/sound/Kconfig
@@ -1,3 +1,5 @@
+menu "Sound support"
+
 config SOUND
 	bool "Enable sound support"
 	help
@@ -53,3 +55,5 @@
 	  Enable the wm8994 audio codec. This is connected via I2S for
 	  audio data and I2C for codec control. At present it only works
 	  with the Samsung I2S driver.
+
+endmenu