riscv: Fix riscv_online_cpu_vec

We shouldn't probe when we already know vector is unsupported and
we should probe when we see we don't yet know whether it's supported.
Furthermore, we should ensure we've set the access type to
unsupported when we don't have vector at all.

Fixes: e7c9d66 ("RISC-V: Report vector unaligned access speed hwprobe")
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250304120014.143628-12-ajones@ventanamicro.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Author: jones-drew

arch/riscv/kernel/unaligned_access_speed.c

@@ -367,10 +367,12 @@ static void check_vector_unaligned_access(struct work_struct *work __always_unus
 
 static int riscv_online_cpu_vec(unsigned int cpu)
 {
-	if (!has_vector())
+	if (!has_vector()) {
+		per_cpu(vector_misaligned_access, cpu) = RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED;
 		return 0;
+	}
 
-	if (per_cpu(vector_misaligned_access, cpu) != RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED)
+	if (per_cpu(vector_misaligned_access, cpu) != RISCV_HWPROBE_MISALIGNED_VECTOR_UNKNOWN)
 		return 0;
 
 	check_vector_unaligned_access_emulated(NULL);