x86/sgx: Define error codes for use by ENCLS[EUPDATESVN]

x86/sgx: Define error codes for use by ENCLS[EUPDATESVN]

Add error codes for ENCLS[EUPDATESVN], then SGX CPUSVN update process can
know the execution state of EUPDATESVN and notify userspace.

EUPDATESVN will be called when no active SGX users is guaranteed. Only add
the error codes that can legally happen. E.g., it could also fail due to
"SGX not ready" when there's SGX users but it wouldn't happen in this
implementation.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Nataliia Bondarevska <bondarn@google.com>