skip mip calculation for non pow2 textures if it's not for a rendertarget

Engine/source/gfx/gfxTextureManager.cpp

@@ -1418,7 +1418,7 @@ void GFXTextureManager::_validateTexParams( const U32 width, const U32 height,
    {
       // If a texture is not power-of-2 in size for both dimensions, it must
       // have only 1 mip level.
-      inOutNumMips = mFloor(mLog2(mMax(width, height))) + 1;
+      inOutNumMips = profile->isRenderTarget() ? mFloor(mLog2(mMax(width, height))) + 1 : 1;
    }
 
    // Check format, and compatibility with texture profile requirements