extcon: arizona: Clear existing button reports before reporting new one

If the user moves directly from one button to another then we won't get a
no buttons pressed event and will therefore end up reporting that two
buttons are simultaneously pressed which isn't supported by the hardware.
Make sure we clear any existing button reports before reporting any new
ones.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

diff --cc drivers/extcon/extcon-arizona.c
Simple merge