[ROCm] update hipify-perl location (#10102)
* [ROCm] update hipify-perl location
Depending on the ROCm version installed, hipify-perl might not always
live in the hard-coded path of /opt/rocm/bin. Use python 3.3's
shutil.which to locate the script.
* provide alternative locations for hipify-perl if not in PATH
* implement hipify-perl search as a function
This avoids running the logic during module import since all builds
import the amd_hipify module.
* fix flake8 errors
