elput: Improve checks for keyboard & pointer devices

elput: Improve checks for keyboard & pointer devices

Some devices reported by libinput show up as both keyboard and mouse,
even tho they are physically only just a keyboard or just a mouse.
When a device gets added, we can verify if it is actually a mouse by
checking if the device has BTN_LEFT (and for keyboards, check
KEY_ENTER). This stops us from getting multiple mouse pointers
reported when we really only have one.

@fix

Signed-off-by: Chris Michael <cp.michael@samsung.com>