[ARM] 5376/1: S3C24XX: Fix sparse errors in platform uncompress.h

Ensure __iomem attribute is __force 'd off in the minimal
__raw_writel() implementation.

Signed-off-by: Simtec Linux Team <linux@simtec.co.uk>
Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>