usb/misc/usbled: Add Riso Kagaku Webmail Notifier

Add support for the "Webmail Notifier" (USB powered LED for signaling
new emails) made by Riso Kagaku Corp. which displays 7 distinct colors.

USB Protocol initially reverse engineered by
	https://code.google.com/p/usbmailnotifier/.

Signed-off-by: Christian Vogel <vogelchr@vogel.cx>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>