Update accel.c

[serossi]

rate calculation and offset subsstraction needs to be done first not after speedcap otherwise rate cap always applys. rate is at this stage still not divided by ms so it will always exceed speedcap therefore it will always apply.

[systemofapwne]

Thank you. I will take a look at it. Sounds reasonable to me TBH.
IIRC, the code has been taken from the original repo, that tried to mimic quake-like acceleration. Maybe I did a mistake when migrating it to leetmouse or there was a bug in the first place.

[serossi]

look the mummy has awaken, every 6000 years she gonna commit and pull,...on github :)

seriously im no longer shure this was the fix.
yes the code is as is in the original repo.

however even if it doesnt fix my initial problem i still believe it would be more "correct" this way.
then again i could be completly wrong there and it might not even matter.