spi: spi-ep93xx: use read,write instead of __raw_* variants

The memory resource used by this driver is ioremap()'d and the normal
read,write calls can be used instead of the __raw_* variants.

Also, remove the inline tag on the helper functions and let the compiler
decide if they are inlined.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: Mark Brown <broonie@linaro.org>