Fix getSwitchState according to device capabilities.

When querying switch state for a given device id, ensure that the device
exposes the given switch in its capabilities, report AKEY_STATE_UNKNOWN
otherwise.
This fix a bug in InputManager that reports an incorrect switch state
(down) when a device exposes at least one switch in its capabilites and
another switch is queried. For example, this can leads in always
reporting LID state open (SW_LID down) if only SW_HEADPHONE_INSERT is
exposed in capabilities.

Change-Id: I4e5265ec02af918c317673789e7948529842aa2d
Signed-off-by: Michaël Burtin <mburtin@gmail.com>