spi: pxa2xx: Remove redundant ->read() and ->write() in struct chip_data

spi: pxa2xx: Remove redundant ->read() and ->write() in struct chip_data

Since the commit 80e270967afe ("spi: pxa2xx: Remove if statement
that is always true in pump_transfers()") the ->read() and ->write()
methods in the struct driver_data are reconfigured for each transfer.
Hence no need to keep the intermediate state in the struct chip_data.

The same applies to n_bytes member of the same data structure.
Get rid of unneeded storage for good.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211122200622.43305-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>