AArch64 special register designations Change range of o0 to [0, 3]

[v01dXYZ]

The documented syntax doesn't allow designation of all possible special registers (e.g. "ICC_CTLR_EL3" designated with "3:6:12:12:4").

clang supports the documented syntax but not gcc.

Both compilers support an alternative syntax with in [0, 3]: s<o0>_<o1>_c<CRm>_c<CRn>_<o2>.

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about: Technical issues, document format problems, bugs in scripts or feature proposal.

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[vhscampos]

Redacted

[vhscampos]

Thanks for the patch.

Can you please add an item in the section "Changes for next release"?