Headset: Ability to hang-up a call from a wired audio headset

Address OPO_52.
The KEY_MEDIA and KEY_VOLUMEUP are mapped to multiple buttons.
That will confuse the input class driver when one button is
pressed while others are released. Fuse all buttons with same
function to one will fix the problem.

Change-Id: Ife63602e68d0fad2813821f0c7e0b6d78cc5d878