defconfig: msm: Enable RRADC driver

Round robin ADC (RRADC) driver is used by clients to
read supported ADC channels on the PMI such as battery ID,
thermistors. Enable RRADC for 8909w target.

Change-Id: I7879b99bf6ff126bdafe54627c6601e690d896c4
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>