msm: ipa: add support to updated wdi3 scratch register2 alone

To update QMAP ID there is no need to start and stop the GSI
channel. Make changes to read only scratch2 register for WDI3
protocol and update the QMAP ID without affecting other registers.

Change-Id: I7f873386fd01d624629fed15b841c6abd558a9ce
Signed-off-by: Chaitanya Pratapa <cpratapa@codeaurora.org>