greybus: HID: Add runtime pm support

Modify HID greybus driver to support runtime PM framework.
The suspend and resume fucntion have been test with tutorial-hid,
e-ink-display and gpbridge-test image by sysfs resume, all HID
buttons work well on suspend/resume.

Testing Done: Compiled and verified on EVT2, DB3.5, GPB test module
              with daughter board, Red module.

Signed-off-by: Philip Yang <yang_philip@projectara.com>
Reviewed-by: David Lin <dtwlin@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>