x86: recognize both avx10.1aux and avx10v1aux

Accept both as names for the same feature. Keeps existing naming as well
as recognize avx10v1aux, aligning with gcc (and Clang eventually).
Subsequently, same applies to v2-aux when added.

gas/
	* config/tc-i386.c: Recognize avx10v1aux as an alias of avx10.1aux.
	* doc/c-i386.texi: Document avx10v1aux alongside avx10.1aux.
	* testsuite/gas/i386/avx10.1-aux-512-cvt.s: Change arch name.
	* testsuite/gas/i386/avx10.1-aux-256-media.s: Ditto.