regmap: mmio: Fix MMIO accessors to avoid talking to IO port

Currently regmap MMIO is inconsistent with IO accessors. I.e.
the Big Endian counterparts are using ioreadXXbe() / iowriteXXbe()
which are not clean implementations of readXXbe().

That said, reimplement current Big Endian MMIO accessors by replacing
ioread()/iowrite() with respective read()/write() and swab() calls.

Note, there are no current in-kernel users that may utilize the
functionality of the IO ports on Big Endian hardware. All drivers
that use regmap MMIO either Little Endian, or they don't map IO
ports in a way that ioreadXX()/iowriteXX() may be utilized.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/20220808203401.35153-5-andriy.shevchenko@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>