spi: cadence_spi: Sync DT bindings with Linux

Adopt the Linux DT bindings. This also fixes an issue
with the indaddrtrig register on the Cadence QSPI
device being programmed with the wrong value for the
socfpga arch.

Tested on TI K2G platform:
Tested-by: Vignesh R <vigneshr@ti.com>

Tested on a socfpga-cyclonev board:
Tested-by: Simon Goldschmidt <sgoldschmidt@de.pepperl-fuchs.com>

Signed-off-by: Jason Rush <jarush@gmail.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Acked-by: Simon Goldschmidt <sgoldschmidt@de.pepperl-fuchs.com>
Acked-by: Marek Vasut <marex@denx.de>