[Bug target/70738] Add -minteger-only option

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70738

--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
AArch64 already has a similar option already.  We've called it
-mgeneral-regs-only.