arm: Various MVE vec_duplicate fixes [PR99647]

arm: Various MVE vec_duplicate fixes [PR99647]

This patch fixes various issues with vec_duplicate in the MVE patterns.
Currently there are two patterns named *mve_mov<mode>. The second of
these is really a vector duplicate rather than a move, so I've renamed
it accordingly.

As it stands, there are several issues with this pattern:
1. The MVE_types iterator has an entry for TImode, but
   vec_duplicate:TI is invalid.
2. The mode of the operand to vec_duplicate is SImode, but it should
   vary according to the vector mode iterator.
3. The second alternative of this pattern is bogus: it allows matching
   symbol_refs (the cause of the PR) and const_ints (which means that it
   matches (vec_duplicate (const_int ...)) which is non-canonical: such
   rtxes should be const_vectors instead and handled by the main vector
   move pattern).

This patch fixes all of these issues, and removes the redundant
*mve_vec_duplicate<mode> pattern.

gcc/ChangeLog:

	PR target/99647
	* config/arm/iterators.md (MVE_vecs): New.
	(V_elem): Also handle V2DF.
	* config/arm/mve.md (*mve_mov<mode>): Rename to ...
	(*mve_vdup<mode>): ... this. Remove second alternative since
	vec_duplicate of const_int is not canonical RTL, and we don't
	want to match symbol_refs.
	(*mve_vec_duplicate<mode>): Delete (pattern is redundant).

gcc/testsuite/ChangeLog:

	PR target/99647
	* gcc.c-torture/compile/pr99647.c: New test.