msm_serial_hs: Handle core interrupt irrespective of wakeup interrupt

Core interrupt should be disabled or enabled during
clock on/off sequence irrespective of wakeup interrupt.

CRs-Fixed: 703047
Change-Id: Ia4fd824f0cc0ff9f054e98d6a52ef3988f9e0254
Signed-off-by: Dilip Kota <c_dkota@codeaurora.org>