efi/libstub: add prototype of efi_tcg2_protocol::hash_log_extend_event()

efi/libstub: add prototype of efi_tcg2_protocol::hash_log_extend_event()

Define the right prototype for efi_tcg2_protocol::hash_log_extend_event()
and add the required structs so we can start using it to measure the initrd
into the TPM if it was loaded by the EFI stub itself.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Link: https://lore.kernel.org/r/20211119114745.1560453-2-ilias.apalodimas@linaro.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>