I don’t see a problem here.  Out of 32 GB RAM you have 31.7 GB available. Only 280 MB is taken by hardware reserved.  Some RAM is always allocated to hardware, mostly an integrated graphics processor. Your allocation is relatively small, is normal and is not a problem. 
I just had to restore my laptop (XPS 15 9510) from an image.  For some reason I thought that I previously had 31.9GB out of 32GB on this laptop...it is showing 31.7GB available and 280MB hardware reserved.  Can someone with similar spec XPS 15 w/ 32GB memory check and let me know if this is the normal amount and, if not, what the issue might be?  I did do a BIOS restore to defaults just to check and nothing changed.  Thanks.
Dell XPS 15 9510 Normal Available Memory (vs. Hardware Reserved)