[ARM] 5215/2: Add support for CM-X300 board

This patch adds core support for CM-X300 board based on PXA300 processor

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>