efi: stmm: Do not return EFI_OUT_OF_RESOURCES on internal errors

When we are low on memory or when the internal API is violated, we
cannot return EFI_OUT_OF_RESOURCES. According to the UEFI standard, that
error code is either related to persistent storage used for the variable
or even not foreseen as possible error (GetVariable e.g.). Use the not
fully accurate but compliant error code EFI_DEVICE_ERROR in those cases.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>