ARM: shmobile: Allow device latencies to be specified directly

Make it possible to specify device start/stop and save/restore
state latencies directy when adding devices to PM domains.  For
this purpose, introduce rmobile_add_device_to_domain_td() whose
third argument is a pointer to a struct gpd_timing_data object
containing device latency data.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>