lib: sbi_hsm: Ensure errors are consistent with spec

HSM functions define when SBI_ERR_INVALID_PARAM should be returned.
Ensure it's not used for reasons that don't meet the definitions by
using the catch-all code, SBI_ERR_FAILED, for those reasons instead.
Also, in one case sbi_hart_suspend() may have returned SBI_ERR_DENIED,
which isn't defined for that function at all. Use SBI_ERR_FAILED for
that case too.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>