Fix off-by-one in mip levels for OpenGL

Engine/source/gfx/gl/gfxGLUtils.h

@@ -30,7 +30,7 @@
 
 inline U32 getMaxMipmaps(U32 width, U32 height, U32 depth)
 {
-   return getMax( getBinLog2(depth), getMax(getBinLog2(width), getBinLog2(height)));
+   return getMax( getBinLog2(depth), getMax(getBinLog2(width), getBinLog2(height))) + 1;
 }
 
 inline GLenum minificationFilter(U32 minFilter, U32 mipFilter, U32 /*mipLevels*/)