msm: camera: isp: Clear only the IRQ bits that are being handled

Do not clear the irq bits that are not handled by the bus irq
controller. Clearing all bits by buf_done irq controller may
clear RUP bit without handling, resulting missing RUP.

CRs-Fixed: 2519423
Change-Id: I65c5efeafbda8f5face50e8c17078269daa37767
Signed-off-by: Pavan Kumar Chilamkurthi <pchilamk@codeaurora.org>