refactor(spm): test_sve_vectors_preserved

Refactor test_sve_vectors_preserved to probe the possible vector length
that the platform implements.
Perform normal/secure world switches and check that SVE state is
preserved for all possible vector lengths.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I90f56d9ae97624ceaaae5a4818045922961e5066
1 file changed