configs: mtmips: refresh for mt7628 based boards

Since mt7620 is added into Kconfig, the CONFIG_SOC_MT7628=y which is
omitted by default must be added back, otherwise make xxx_defconfig for
these boards will be configured for mt7620 platform.

Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/configs/vocore2_defconfig b/configs/vocore2_defconfig
index acb9abf..e255829 100644
--- a/configs/vocore2_defconfig
+++ b/configs/vocore2_defconfig
@@ -10,6 +10,7 @@
 CONFIG_SPL=y
 CONFIG_SYS_BOOTCOUNT_SINGLEWORD=y
 CONFIG_ARCH_MTMIPS=y
+CONFIG_SOC_MT7628=y
 CONFIG_BOARD_VOCORE2=y
 CONFIG_DEFAULT_DEVICE_TREE="vocore_vocore2"
 CONFIG_RESTORE_EXCEPTION_VECTOR_BASE=y