spi: spi-mem: Fix inverted logic in op sanity check

On r8a7791/koelsch:

    m25p80 spi0.0: error -22 reading 9f
    m25p80: probe of spi0.0 failed with error -22

Apparently the logic in spi_mem_check_op() is wrong, rejecting the
spi-mem operation if any buswidth is valid, instead of invalid.

Fixes: 38058322 ("spi: spi-mem: Add extra sanity checks on the op param")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>