- Rephrase the comments about tx/rx_nbits validity checks,
  - Remove the stale comment about SPI_3WIRE (the code it refers to was
    removed in commit 368ca4e0 ("spi:
    Eliminate 3WIRE spi_transfer check")).
Signed-off-by: NGeert Uytterhoeven <geert+renesas@linux-m68k.org>
Signed-off-by: NMark Brown <broonie@linaro.org>