PowerPC: Add support for Power11 options

binutils/
	* doc/binutils.texi (PowerPC -M option): Mention power11 and pwr11.

gas/
	* config/tc-ppc.c: (md_show_usage): Mention -mpower11 and -mpwr11.
	* doc/c-ppc.texi: Likewise.

opcodes/
	* ppc-dis.c (ppc_opts): Add "power11" and "pwr11" entries.
	(powerpc_init_dialect): Default to "power11".

(cherry picked from commit 4199cf1e)