ARM: S5P: Regoster clk_xusbxti clock for hsotg driver

The clk_xusbxti clock is added to the list of clocks to be
registred during boot time clock registration.

Signed-off-by: Thomas Abraham <thomas.ab@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
[ben-linux@fluff.org: edited title]
Signed-off-by: Ben Dooks <ben-linux@fluff.org>