regulator: qpnp-oledb: Add revid support for OLEDB driver

Add PMIC revid support to identify the PMIC subtype for OLEDB driver.
This is useful to enable the functionalities/features that are specific to
certain PMICs like PM660A.

Change-Id: I4539955abb29fe37256e21ac507db646953e0abf
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>