The minimal requirement for running Vector subextension on Linux is
ZVE32X. So change the test accordingly to run prctl as long as it find
it.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20240510-zve-detection-v5-8-0711bdd26c12@sifive.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>