UPSTREAM: HID: plantronics: Update to map volume up/down controls

Update Kconfig with enhanced help text for hid-plantronics driver.

Update hid-plantronics.c to identify device type and correctly map
either the vendor unique or consumer control volume up/down usages
to KEY_VOLUMEUP and KEY_VOLUMEDOWN events. Unmapped usages are ignored
to prevent core mapping of unknown usages to random mouse events.

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>

BUG=chromium:417438
TEST=Use Plantronics device, observe volume keys affect system volume.

(cherry picked from commit 81bb773faed7f5f0e82f14cdfcfe4e89fbea0e19)
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>

Change-Id: I376d67939235c6b5781ec977b5516c773ec1b8a0
Reviewed-on: https://chromium-review.googlesource.com/284671
Tested-by: Dmitry Torokhov <dtor@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Commit-Queue: Dmitry Torokhov <dtor@chromium.org>
(cherry picked from commit f5ca59e1eb804f7699b55cede4bc36d0e58044ad)
Reviewed-on: https://chromium-review.googlesource.com/284946
2 files changed