spi: sh-msiof: Correct RX FIFO size for R-Car Gen2

spi: sh-msiof: Correct RX FIFO size for R-Car Gen2

According to Renesas Technical Updates TN-RCS-S068A/E, the MSIOF receive
FIFOs on R-Car Gen2 SoCs have room for 128 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/fd11933f932df81d84f417a21e2179bd4fdcfdc1.1747401908.git.geert+renesas@glider.be
Signed-off-by: Mark Brown <broonie@kernel.org>