In sun6i_spi_transfer_one() the driver ensures that the length of the transfer
is smaller or equal to SUN6I_MAX_XFER_SIZE. This means the masking of the
length to SUN6I_MAX_XFER_SIZE can be skipped when writing the transfer length
into the registers.

This patch removes the useless masking of the transfer length to
SUN6I_MAX_XFER_SIZE.
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20200706143443.9855-5-mkl@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>