drm/ingenic: Kconfig: select REGMAP and REGMAP_MMIO

Otherwise its failed to pass basic compile test on platform without
REGMAP_MMIO selected by defconfig

make -j$(nproc) ARCH=mips CROSS_COMPILE=mips64el-linux-gnuabi64-

  SYNC    include/config/auto.conf.cmd
  Checking missing-syscalls for N32
  CALL    scripts/checksyscalls.sh
  Checking missing-syscalls for O32
  CALL    scripts/checksyscalls.sh
  CALL    scripts/checksyscalls.sh
  MODPOST Module.symvers
ERROR: modpost: "__devm_regmap_init_mmio_clk" [drivers/gpu/drm/ingenic/ingenic-drm.ko] undefined!
make[1]: *** [scripts/Makefile.modpost:136: Module.symvers] Error 1
make: *** [Makefile:1978: modpost] Error 2

V2: Order alphabetically
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230607110650.569522-1-suijingfeng@loongson.cn

drivers/gpu/drm/ingenic/Kconfig

@@ -9,6 +9,8 @@ config DRM_INGENIC
 	select DRM_PANEL_BRIDGE
 	select DRM_KMS_HELPER
 	select DRM_GEM_DMA_HELPER
+	select REGMAP
+	select REGMAP_MMIO
 	select VT_HW_CONSOLE_BINDING if FRAMEBUFFER_CONSOLE
 	help
 	  Choose this option for DRM support for the Ingenic SoCs.