drm/ast: Fix test for VGA enabled

[ Upstream commit 905f21a4 ]

The test to see if VGA was already enabled is doing an unnecessary
second test from a register that may or may not have been initialized
to a valid value. Remove it.
Signed-off-by: Y.C. Chen <yc_chen@aspeedtech.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: <stable@vger.kernel.org>
Acked-by: Joel Stanley <joel@jms.id.au>
Tested-by: Y.C. Chen <yc_chen@aspeedtech.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

drivers/gpu/drm/ast/ast_post.c

@@ -58,13 +58,9 @@ bool ast_is_vga_enabled(struct drm_device *dev)
 		/* TODO 1180 */
 	} else {
 		ch = ast_io_read8(ast, AST_IO_VGA_ENABLE_PORT);
-		if (ch) {
-			ast_open_key(ast);
-			ch = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb6, 0xff);
-			return ch & 0x04;
-		}
+		return !!(ch & 0x01);
 	}
-	return 0;
+	return false;
 }
 
 static const u8 extreginfo[] = { 0x0f, 0x04, 0x1c, 0xff };