USB: Add initial S5P EHCI driver

This patch adds host USB high speed driver for samsung S5P series. This
is initial driver and we need additional implementation to support some
functions like power management.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>