This function allows the port's scheduling policy to be changed. Some
tty ports (like Bluetooth ones), need a higher priority to reduce
jitter.
Bug: 36106419
Test: Bluetooth audio
Change-Id: If11e21c55924314910d602573c735c6afae09709
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>