HID: corsair: Add Corsair Vengeance K90 driver

This patch implements a HID driver for the Corsair Vengeance K90 keyboard.

It fixes the behaviour of the keys using incorrect HID usage codes and exposes
the macro playback mode and current profile to the user space through sysfs
attributes. It also adds two LED class devices controlling the "record" LED and
the backlight.

Signed-off-by: Clément Vuchener <clement.vuchener@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-ids.h

@@ -251,6 +251,9 @@
 #define USB_DEVICE_ID_CODEMERCS_IOW_FIRST	0x1500
 #define USB_DEVICE_ID_CODEMERCS_IOW_LAST	0x15ff
 
+#define USB_VENDOR_ID_CORSAIR		0x1b1c
+#define USB_DEVICE_ID_CORSAIR_K90	0x1b02
+
 #define USB_VENDOR_ID_CREATIVELABS	0x041e
 #define USB_DEVICE_ID_PRODIKEYS_PCMIDI	0x2801