mips: mtmips: select essential drivers in Kconfig

Some drivers (clk, pinctrl, reset, ...) are necessary for reset of the
system, they should be always selected.

Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
diff --git a/arch/mips/mach-mtmips/Kconfig b/arch/mips/mach-mtmips/Kconfig
index 4af2d54..c8dcf19 100644
--- a/arch/mips/mach-mtmips/Kconfig
+++ b/arch/mips/mach-mtmips/Kconfig
@@ -13,6 +13,8 @@
 config SOC_MT7628
 	bool "MT7628"
 	select MIPS_L1_CACHE_SHIFT_5
+	select PINCTRL_MT7628
+	select MTK_SERIAL
 	help
 	  This supports MediaTek MT7628/MT7688.