spi: Fix spelling typos and acronyms capitalization

Fix
  - spelling typos
  - capitalization of acronyms
in the comments.

While at it, fix the multi-line comment style.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230710154932.68377-16-andriy.shevchenko@linux.intel.com


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