Remove overly restrictive assert in adam (#80222)
This is causing issues if the user has the step on cuda for a good reason.
These assert prevents code that used to run just fine to fail.
Note that this is a pretty bad thing to do for performance though so it is ok to try and push users away from doing it.
For the 1.12.1 milestone: this is not asking for a dot release to fix this (as this is bad practice anyways). But it would be a great thing to add if we do one: it is very low risk and will prevent breakage for users.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80222
Approved by: https://github.com/jbschlosser, https://github.com/ngimel
