Ok... I just had the same issue and after an hour of trying to figure this
out... reading threads in forums... and nobody had a reliable solution... I got
it...! LOL
Anyway, it's as simple as hooking up your iPhone to your computer and getting
into iTunes > go to your iPhone > go to Photos > Put a check in the box
for "Sync Photos from". Now make sure you pick your folder that you have
previously used for photos. Otherwise, you can do what I did and just said "To
heck with it" and created a blank folder with zero pictures in it. Last, just
hit "Apply" down at the bottom of iTunes. Voila! Problem solved! No more
spinning, no more downloading, no more killing the battery and no more
headache!
Essentially, all you're doing is manually RE-SYNCING your photos and
overriding the iCloud sync download to your iPhone.
P.S. - If you do as I did with the blank folder with zero photos, your
phone's Camera Roll will have 0 photos in it. And if you had seperate Albums
that you have created... they will be gone too. So, if you want to make sure to
keep all of your photos and albums... MAKE SURE YOU SELECT THOSE FOLDERS THROUGH
ITUNES BEFORE YOU HIT "APPLY"!