pinctrl: sprd: fix build errors and dependencies

Fix build errors when CONFIG_OF is not enabled.
Also, the pinctrl-sprd-sc9860 driver uses functions from the pinctrl-sprd
driver, so the former should depend on the latter driver.

../drivers/pinctrl/sprd/pinctrl-sprd.c: In function 'sprd_dt_node_to_map':
../drivers/pinctrl/sprd/pinctrl-sprd.c:290:2: error: implicit declaration of function 'pinconf_generic_parse_dt_config' [-Werror=implicit-function-declaration]
  ret = pinconf_generic_parse_dt_config(np, pctldev, &configs,
  ^
../drivers/pinctrl/sprd/pinctrl-sprd.c: At top level:
../drivers/pinctrl/sprd/pinctrl-sprd.c:844:44: error: array type has incomplete element type
 static const struct pinconf_generic_params sprd_dt_params[] = {
                                            ^
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Baolin Wang <baolin.wang@spreadtrum.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>