configs: Re-sync HUSH options

Move all cases of CONFIG_SYS_HUSH_PARSER out of the config.h files.  Remove
all cases of CONFIG_SYS_PROMPT_HUSH_PS2 as everyone uses the default.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/icon_defconfig b/configs/icon_defconfig
index 39b5185..a55bbdb 100644
--- a/configs/icon_defconfig
+++ b/configs/icon_defconfig
@@ -2,5 +2,6 @@
 CONFIG_4xx=y
 CONFIG_TARGET_ICON=y
 CONFIG_OF_BOARD_SETUP=y
+CONFIG_HUSH_PARSER=y
 CONFIG_SYS_NS16550=y
 CONFIG_OF_LIBFDT=y