Some Plantronics headset as the below send an unexcept opposite
volume key's HID report for each volume key press after 200ms, like
unecepted Volume Up Key following Volume Down key pressed by user.
This patch adds a quirk to hid-plantronics for these devices, which
will ignore the second unexcepted opposite volume key if it happens
within 220ms from the last one that was handled.
    Plantronics EncorePro 500 Series  (047f:431e)
    Plantronics Blackwire_3325 Series (047f:430c)

The patch was tested on the mentioned model, it shouldn't affect
other models, however, this quirk might be needed for them too.
Auto-repeat (when a key is held pressed) is not affected per test
result.

Cc: stable@vger.kernel.org
Signed-off-by: Wade Wang <wade.wang@hp.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>