efi_loader: correctly handle no tpm device error

When the TCG2 protocol is installed in efi_tcg2_register(),
TPM2 device must be present.
tcg2_measure_pe_image() expects that TCP2 protocol is installed
and TPM device is available. If TCG2 Protocol is installed but
TPM device is not found, tcg2_measure_pe_image() returns
EFI_SECURITY_VIOLATION and efi_load_image() ends with failure.

The same error handling is applied to
efi_tcg2_measure_efi_app_invocation().

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>