Disable TX IQ calibration, it was prematurely enabled in
previous versions.
Cc: Paul Shaw <Paul.Shaw@Atheros.com> Cc: Thomas Hammel <Thomas.Hammel@atheros.com> Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>