spi: mchp-pci1xxxx: Fix SPI transactions not working after suspend and resume

spi: mchp-pci1xxxx: Fix SPI transactions not working after suspend and resume

pci1xxxx_spi_resume API masks SPI interrupt bit which prohibits interrupt
from coming to the host at the end of the transaction after suspend-resume.
This patch unmasks this bit at resume.

Fixes: 1cc0cbea7167 ("spi: microchip: pci1xxxx: Add driver for SPI controller of PCI1XXXX PCIe switch")
Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Link: https://lore.kernel.org/r/20230404171613.1336093-3-tharunkumar.pasumarthi@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>