Fix headset media button long press cannot reject call.

When making phone call with headset, another call incoming, long press
headset media button to reject new incoming call, call cannot be
rejected and first call will be muted. This is because SHORT_PRESS
should not be judged by ACTION_UP event's repeatCount which will be
always 0. Actually, ACTION_DOWN event's repeatCount only increases when
LONG_PRESS is performed.

Also, swapping SHORT and LONG press actions between MUTE and HANGUP to
match more of the existing devices.

Test: manual
Change-Id: I7a1270925f7148dac81fa5e58b232a886c57236a
Merged-In: I6ec28a2676a86cfa06819e297136ff413c14f169
Fix: 30012668