Move CONFIG_SYS_HUSH_PARSER to Kconfig for last 4 boards

I still see some defines of this config in board headers.  Move them
to defconfigs (+ renaming to CONFIG_HUSH_PARSER) to complete this
migration.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/configs/tplink_wdr4300_defconfig b/configs/tplink_wdr4300_defconfig
index a69c0b6..ed6239b 100644
--- a/configs/tplink_wdr4300_defconfig
+++ b/configs/tplink_wdr4300_defconfig
@@ -7,6 +7,7 @@
 CONFIG_BOARD_TPLINK_WDR4300=y
 CONFIG_DEFAULT_DEVICE_TREE="tplink_wdr4300"
 CONFIG_BOOTDELAY=3
+CONFIG_HUSH_PARSER=y
 # CONFIG_CMD_ELF is not set
 # CONFIG_CMD_IMLS is not set
 # CONFIG_CMD_XIMG is not set