drm/ast: Remove AST_TX_ITE66121 constant

The ITE66121 is an HDMI transmitter chip. There's no code for
detecting or programming the chip within ast. Remove the enum
constant.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220207141544.30015-4-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_drv.h

@@ -69,7 +69,6 @@ enum ast_chip {
 enum ast_tx_chip {
 	AST_TX_NONE,
 	AST_TX_SIL164,
-	AST_TX_ITE66121,
 	AST_TX_DP501,
 };