[ Upstream commit 37e376df ]

Add a mapping for Push-To-Talk joystick trigger button.

Tested on ChromeBox/ChromeBook with various Plantronics devices.
Signed-off-by: Terry Junge <terry.junge@plantronics.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>