HID: Check for EINTR in uhid_event() and fix return value evaluation
uhid_event() returns 0 in the normal case. Commit 39a6ffe0
results in the polling thread to be exited.
Bug: 28942565
Change-Id: Id0aff2958bc7c2704ba340aa0ff7848afb8dcf80
(cherry picked from commit 108e10af)