Bluetooth: uhid: Prevent deadlock while waiting for response

This patch prevents deadlock between userspace and kernel space uhid
driver by releasing the held mutex(s) before waiting for response for
set/get report. Without this there was potential deadlock in code
that lead to unnecessary wait for 5 seconds for response for set report
to be received from user space which could not come, as mutex was held
leading to blockage of read and further write.

Change-Id: I3f003f33bdf2a0aeb4821598c667cbf61db83b9b
CRs-Fixed: 963213
Signed-off-by: Hemant Gupta <hemantg@codeaurora.org>