spi: f_ospi: Add missing spi_mem_default_supports_op() helper

The .supports_op() callback function returns true by default after
performing driver-specific checks. Therefore the driver cannot apply
the buswidth in devicetree.

Call spi_mem_default_supports_op() helper to handle the buswidth
in devicetree.

Fixes: 1b74dd64

 ("spi: Add Socionext F_OSPI SPI flash controller driver")
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/20230322023101.24490-1-hayashi.kunihiko@socionext.com
Signed-off-by: Mark Brown <broonie@kernel.org>