[HIP] Add an --offload-arch option to hip-tpl.py

[jmmartinez]

We add a --offload-arch=... option, that we can use to switch the target architecture. This can be a string such as 'gfx{version}', or 'amdgcnspirv'.

This option defaults to 'gfx90a' such that if it is not specified, we keep the old behavior ('gfx90a' was hardcoded).

If we pass an incorrect option we get:

$ ./hip-tpl.py --offload-arch=aaa
usage: hip-tpl.py [-h] [--offload-arch OFFLOAD_ARCH]
hip-tpl.py: error: argument --offload-arch: invalid amdgpu_target value: 'aaa'

And for the help:

$ ./hip-tpl.py --help
usage: hip-tpl.py [-h] [--offload-arch OFFLOAD_ARCH]

options:
  -h, --help            show this help message and exit
  --offload-arch OFFLOAD_ARCH
                        Offload architecture to be forwarded to AMDGPU_ARCHS during the test suite configuration. e.g. gfx90a, gfx1010, amdgcnspirv