spi: s3c64xx: prepare for a different flavor of iowrite rep

spi: s3c64xx: prepare for a different flavor of iowrite rep

There are SoCs (gs101) that allow only 32 bit register accesses. As the
requirement is rare enough, for those SoCs we'll open code in the driver
some s3c64xx_iowrite{8,16}_32_rep() accessors. Prepare for such addition.

Suggested-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20240207111516.2563218-3-tudor.ambarus@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>