pinctrl: sprd: Change to use devm_platform_ioremap_resource()

The devm_platform_ioremap_resource() function wraps platform_get_resource()
and devm_ioremap_resource() in a single helper, thus use it to simplify
the code.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/ff410d312ed0047b5a36e5113daf7df78bcf1aa8.1564048446.git.baolin.wang@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>