spi: topcliff-pch: Prevent usage of potentially stale DMA device

DMA device is expected to be available while SPI transfer is ongoing.

Prevent usage of potentially stale DMA device by keeping reference
count till the end of the transfer.

Fixes: 4d986ffa

 ("spi: add missing pci_dev_put() before return")
Reported-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220307173740.80996-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>