defconfig: msm: Use RCU_NOCB for RCU subsystem for sdm660

Use per CPU NOCB threads to process RCU callbacks, rather than processing
the callbacks in softirq context. Processing large number of callbacks
in softirq context may result in delayed execution of other softirqs, so
remove processing of callbacks from softirq context.

Change-Id: I361221ea302c84d626122538d383f549ea9cea0d
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>