spi: tegra114: add support for TX and RX trimmers

Tegra SPI master controller has programmable trimmers to adjust the
data with respect to the clock.

These trimmers are programmed in TX_CLK_TAP_DELAY and RX_CLK_TAP_DELAY
fields of COMMAND2 register.

SPI TX trimmer is to adjust the outgoing data with respect to the
outgoing clock and SPI RX trimmer is to adjust the loopback clock with
respect to the incoming data from the slave device.

These trimmers vary based on trace lengths of the platform design for
each of the slaves on the SPI bus and optimal value programmed is from
the platform validation across PVT.

This patch adds support for configuring TX and RX clock delay trimmers
through the device tree properties.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>