[ARM] 4340/1: iop: fix iop_getttimeoffset

Fix a typo which causes a necessary cpwait to be missed on iop3xx, Michael
Brunner <mibru@gmx.de>

Save a register in the assembly routine, rmk

Cc: Lennert Buytenhek <kernel@wantstofly.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>