mmc: renesas_sdhi: improve registering irqs

The probe() function is convoluted enough, so merge sanity checks for
number of irqs into one place. Also, change the error code for 'no irq'
because ENXIO will not print a warning from the driver core.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20250331064400.16677-2-wsa+renesas@sang-engineering.com


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