Revert "[X86][AMX] Try to hoist AMX shapes' def"

This reverts commit 90118563.

Reason: Broke the MSan buildbots.
https://lab.llvm.org/buildbot/#/builders/5/builds/6967/steps/9/logs/stdio

More details can be found in the original phabricator review:
https://reviews.llvm.org/D101067