riscv: hwprobe: add zve Vector subextensions into hwprobe interface

riscv: hwprobe: add zve Vector subextensions into hwprobe interface

The following Vector subextensions for "embedded" platforms are added
into RISCV_HWPROBE_KEY_IMA_EXT_0:
 - ZVE32X
 - ZVE32F
 - ZVE64X
 - ZVE64F
 - ZVE64D

Extensions ending with an X indicates that the platform doesn't have a
vector FPU.
Extensions ending with F/D mean that whether single (F) or double (D)
precision vector operation is supported.
The number 32 or 64 follows from ZVE tells the maximum element length.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Clément Léger <cleger@rivosinc.com>
Link: https://lore.kernel.org/r/20240510-zve-detection-v5-6-0711bdd26c12@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>