spi: fsl-cpm: Properly define and use IO pointers

Sparse reports several issues with IO pointers.

Fix it by adding missing __iomem flags and using iowriteXXbe()
generic helpers instead of the powerpc specific out_beXX() ones.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307252052.7RqHxFZj-lkp@intel.com/


Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/18a65dca9134f6fc35932408066d4a8284cbfa65.1691571190.git.christophe.leroy@csgroup.eu


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