[hid][buttons] Use edge instead of level interrupts

Edge interrupts do not require the state machine handling required by
level interrupts in the kernel and work as well in hid-buttons.
Issues with level interrupt handling has been seen at least on one device
that is being tracked by ZX-3077.  Since we have support for edge interrupts
in all HW that uses buttons today, switched to edge.

Test: hid uapp in astro and mt8167s.

Change-Id: I36725ee87baa7b007b1c523c17d2daca5efda65b