spi: cadence_qspi: Clean up the #define names

spi: cadence_qspi: Clean up the #define names

A lot of the #defines are for single bits in a register, where the
name has _MASK on the end. Since this can be used for both a mask
and the value, remove _MASK from them.

Whilst doing so, also remove the unnecessary brackets around the
constants.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>