spi: dw: Convert to using the Bitfield access macros

spi: dw: Convert to using the Bitfield access macros

The driver has been using the offset/bitwise-shift-based approach for the
CSR fields R/W operations since it was merged into the kernel. It can be
simplified by using the macros defined in the linux/bitfield.h and
linux/bit.h header files like BIT(), GENMASK(), FIELD_PREP(), FIELD_GET(),
etc where it is required, for instance in the cached cr0 preparation
method. Thus in order to have the FIELD_*()-macros utilized we just need
to convert the macros with the CSR-fields offsets to the masks with the
corresponding registers fields definition. That's where the GENMASK() and
BIT() macros come in handy. After that the masks can be used in the
FIELD_*()-macros where it's appropriate.

We also need to convert the macros with the CRS-bit flags using the manual
bitwise shift operations (x << y) to using the BIT() macro. Thus we'll
have a more coherent set of the CSR-related macros.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20211115181917.7521-5-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Mark Brown <broonie@kernel.org>