media: imon: grab lock earlier in imon_ir_change_protocol()

media: imon: grab lock earlier in imon_ir_change_protocol()

Move mutex_trylock() in imon_ir_change_protocol() to the beginning,
for memcpy() which modifies ictx->usb_tx_buf should be protected by
ictx->lock.

Also, verify at the beginning of send_packet() that ictx->lock is held
in case send_packet() is by error called from imon_ir_change_protocol()
when mutex_trylock() failed due to concurrent requests.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>