ARM: 5937/1: Add support for EP9315 based Snapper CL15 board

Add support for Bluewater Systems EP9315 based Snapper CL15 single board
computer module.

Signed-off-by: Ryan Mallon <ryan@bluewatersys.com>
Acked-by: Hartley Sweeten <hartleys@visionengravers.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>