media: rc: IR signal for Panasonic air conditioner too long

The IR signal to control the Panasonic ACXA75C00600 air conditioner has
439 pulse/spaces. Increase limit to make it possible to transmit signal.

Reported-by: Takashi Kanamaru <neuralassembly@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>