input: sensors: interrupt and power enabling pins are optional

The interrupt and power enabling pin configurations are not
required properties since some design doesn't have gpio for
interrupt and power enabling.

CRs-fixed: 655796
Change-Id: If66bd0cd1a75dea3ef8c65439218cf8e096b7d5d
Signed-off-by: Bingzhe Cai <bingzhec@codeaurora.org>