In some cases reset_sccr1() can be called when no message available.
This means that there is no associated chip to receive that message
and hence no threshold needs to be set. Adapt the function to such
cases.

Fixes: 3bbdc083 ("spi: pxa2xx: Reuse int_stop_and_reset() in couple of places")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210721121520.62605-1-andriy.shevchenko@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>