spi: fsl-espi: improve and simplify interrupt handler

Simplify the interrupt handler a little. In addition don't call
fsl_espi_cpu_irq() if no event bit is set.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed