Bug in existing code causes synchro control to be set +32 if request
line greater than 63 is used.

Also clean up the function a bit by removing extra parens and
clearing the bits at before write.

Reported by Wenbiao Wang.
Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>