drm/ast: Remove dead else branch in POST code

According to the chip detection in ast_detect_chip(), AST2300 and
later always have a PCI revision of 0x20 or higher. Therefore the
code in ast_set_def_ext_reg() can not use the else branch when
selecing the EXT register values. Remove the dead branch and the
related values.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Jocelyn Falempe <jfalempe@redhat.com> # AST2600
Link: https://patchwork.freedesktop.org/patch/msgid/20230621130032.3568-5-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_post.c

@@ -64,28 +64,22 @@ bool ast_is_vga_enabled(struct drm_device *dev)
 }
 
 static const u8 extreginfo[] = { 0x0f, 0x04, 0x1c, 0xff };
-static const u8 extreginfo_ast2300a0[] = { 0x0f, 0x04, 0x1c, 0xff };
 static const u8 extreginfo_ast2300[] = { 0x0f, 0x04, 0x1f, 0xff };
 
 static void
 ast_set_def_ext_reg(struct drm_device *dev)
 {
 	struct ast_device *ast = to_ast_device(dev);
-	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	u8 i, index, reg;
 	const u8 *ext_reg_info;
 
 	/* reset scratch */
 	for (i = 0x81; i <= 0x9f; i++)
 		ast_set_index_reg(ast, AST_IO_CRTC_PORT, i, 0x00);
 
-	if (ast->chip == AST2300 || ast->chip == AST2400 ||
-	    ast->chip == AST2500) {
-		if (pdev->revision >= 0x20)
-			ext_reg_info = extreginfo_ast2300;
-		else
-			ext_reg_info = extreginfo_ast2300a0;
-	} else
+	if (ast->chip == AST2300 || ast->chip == AST2400 || ast->chip == AST2500)
+		ext_reg_info = extreginfo_ast2300;
+	else
 		ext_reg_info = extreginfo;
 
 	index = 0xa0;