mmc: mmc_spi: Use already parsed IRQ

SPI core already parses and maps IRQ for us if provided.
Use it instead of double parsing in mmc_spi_get_pdata().

Due to above, change condition, since SPI core can hold
an error pointer as invalid IRQ.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210419112459.25241-5-andriy.shevchenko@linux.intel.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>