spi: bcm63xx: extend error condition to `delay` as well

The driver errors out if `delay_usecs` is non-zero. This error condition
should be extended to the new `delay` field, to account for when it will be
used.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-19-alexandru.ardelean@analog.com


Signed-off-by: Mark Brown <broonie@kernel.org>