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/gurnard_defconfig b/configs/gurnard_defconfig
index 80f0013..d74757c 100644
--- a/configs/gurnard_defconfig
+++ b/configs/gurnard_defconfig
@@ -5,6 +5,7 @@
 CONFIG_FIT=y
 CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9G45"
 CONFIG_BOOTDELAY=3
+CONFIG_HUSH_PARSER=y
 # CONFIG_CMD_BDI is not set
 # CONFIG_CMD_IMI is not set
 # CONFIG_CMD_IMLS is not set