spi: sh-msiof: Correct RX FIFO size for R-Car Gen3

spi: sh-msiof: Correct RX FIFO size for R-Car Gen3

According to the R-Car Gen3 Hardware Manual Errata for Rev 0.55 of
September 28, 2017, the MSIOF receive FIFOs on R-Car Gen3 SoCs have room
for 256 words of 32 bits.

Note that this change has no actual impact on the behavior of the
driver, as SPI_CONTROLLER_MUST_TX is set, and transfer size is currenty
limited to the minimum of the transmit and receive FIFO sizes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/6f74508ea4681aa0b7c6bf6810eab026725e75a3.1747401908.git.geert+renesas@glider.be
Signed-off-by: Mark Brown <broonie@kernel.org>