33.4.1. gem5 baremetal arm CLI args

Currently not supported, so we just hardcode argc 0 on the arm baremetal bootloader.

I think we have to keep the CLI args below 32 GiB, otherwise argc cannot be correctly setup. But currently the gem5 text segment is exactly at 32 GiB, and we always place the CLI args higher in the Baremetal linker script.