Revert "Make libminuitwrp compile"

This reverts commit a27d02fab9d6feb793cdcd6146f2655658f36f2b.

Change-Id: I62d143044749f101cd70fef048057f896e46c208
diff --git a/minuitwrp/minui.h b/minuitwrp/minui.h
index 699b08c..cb9f8a3 100644
--- a/minuitwrp/minui.h
+++ b/minuitwrp/minui.h
@@ -17,16 +17,7 @@
 #ifndef _MINUI_H_
 #define _MINUI_H_
 
-typedef struct {
-    int width;
-    int height;
-    int row_bytes;
-    int pixel_bytes;
-    unsigned char* data;
-} GRSurface;
-
-typedef GRSurface* gr_surface;
-
+typedef void* gr_surface;
 typedef unsigned short gr_pixel;
 
 #define FONT_TYPE_TWRP 0