HID: hid debug from hid-debug.h to hid layer

hid-debug.h contains a lot of code, and should not therefore
be a header.

This patch moves the code to generic hid layer as .c source, and
introduces CONFIG_HID_DEBUG to conditionally compile it, instead
of playing with #define DEBUG and including hid-debug.h.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index ec796ad..850788f 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -22,5 +22,19 @@
 
 	  If unsure, say Y
 
+config HID_DEBUG
+	bool "HID debugging support"
+	depends on HID
+	---help---
+	This option lets the HID layer output diagnostics about its internal
+	state, resolve HID usages, dump HID fields, etc. Individual HID drivers
+	use this debugging facility to output information about individual HID
+	devices, etc.
+
+	This feature is useful for those who are either debugging the HID parser
+	or any HID hardware device.
+
+	If unsure, say N
+
 endmenu