configs: mt7629_rfb: use arm arch timer instead of mtk timer

This patch changes mt7629_rfb to use ARM's generic arch timer instead of
MediaTek's soc timer.

diff --git a/configs/mt7629_rfb_defconfig b/configs/mt7629_rfb_defconfig
index 0dceafd..d6a7c84 100644
--- a/configs/mt7629_rfb_defconfig
+++ b/configs/mt7629_rfb_defconfig
@@ -1,4 +1,5 @@
 CONFIG_ARM=y
+CONFIG_SYS_ARCH_TIMER=y
 CONFIG_SYS_THUMB_BUILD=y
 CONFIG_ARCH_MEDIATEK=y
 CONFIG_SYS_TEXT_BASE=0x41e00000
@@ -67,9 +68,6 @@
 CONFIG_SYSRESET=y
 CONFIG_SPL_SYSRESET=y
 CONFIG_SYSRESET_WATCHDOG=y
-CONFIG_TIMER=y
-CONFIG_SPL_TIMER=y
-CONFIG_MTK_TIMER=y
 CONFIG_WDT_MTK=y
 CONFIG_LZMA=y
 # CONFIG_EFI_LOADER is not set