spi: cadence: Remove _MASK and _OFFSET suffix

Remove the _MASK and _OFFSET from the macros.
It improves readability, removes some checkpatch
error for exceeding 80 chars  and also prevents some
linebreaks.

Signed-off-by: Shubhrajyoti Datta <shubhraj@xilinx.com>
Signed-off-by: Mark Brown <broonie@kernel.org>