drivers: pinctrl: Add support for read/write of QUP registers

Add support to read and write QUP mode registers in TLMM block.

Change-Id: I9878af50f6920c577fa74047e01e9b37c0542dd1
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>