mfd: qcom-i2c-pmic: prepare for shared interrupt

The interrupt coming to smb1381 and other i2c pmic's could be shared
with direct charge chip. Update the code to reflect that.

CRs-Fixed: 1059549
Change-Id: I4d12ff4d1d87aa984f601760b26b3413484f501a
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>