[AMDGPU] Regenerate checks for test/CodeGen/AMDGPU/bf16.ll (llvm#161069)

Looks like there were some checks leftover from before the GFX1250TRUE16
run line was disabled. These were causing problems downstream. Not sure
why update_llc_test_checks did not clean these up.

I removed all existing checks and re-ran update_llc_test_checks.

Author: macurtis-amd