pinctrl: sprd: Fix the kconfig warning

pinctrl: sprd: Fix the kconfig warning

On X86 plaform, if the CONFIG_OF is not selected, and set the
CONFIG_SPRD_SC9860 as 'm', that will cause below waring:

WARNING: unmet direct dependencies detected for PINCTRL_SPRD
  Depends on [n]: PINCTRL [=y] && OF [=n] && (ARCH_SPRD || COMPILE_TEST [=y])
  Selected by [m]:
  - PINCTRL_SPRD_SC9860 [=m] && PINCTRL [=y]

Thus move the configuration dependency under CONFIG_PINCTRL_SPRD_SC9860
to fix the warning.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/eeb12d7843fb06f80e19f98eb25711231c3b610f.1583205650.git.baolin.wang7@gmail.com
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>