regulator: qpnp-oledb: Clear SPARE_CTL register during disable

OLEDB_SPARE_CTL register bit is set by the PBS during the display enable
and is used during the display suspend to trigger the PBS event.
Hence, move clearing of the OLEDB_SPARE_CTL register to regulator disable.
Also enable the force_pd_ctl only for DRAX-A revisions <=2.0.

Change-Id: I339cefc91f94f772bc4f84e85f2471e1a73e4aed
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>