efi/libstub: fix prototype of efi_tcg2_protocol::get_event_log()

efi_tcg2_protocol::get_event_log() takes a protocol pointer as the
first argument, not a EFI handle.
Signed-off-by: NArd Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/libstub/efistub.h

@@ -672,7 +672,7 @@ typedef union efi_tcg2_protocol efi_tcg2_protocol_t;
 union efi_tcg2_protocol {
 	struct {
 		void *get_capability;
-		efi_status_t (__efiapi *get_event_log)(efi_handle_t,
+		efi_status_t (__efiapi *get_event_log)(efi_tcg2_protocol_t *,
 						       efi_tcg2_event_log_format,
 						       efi_physical_addr_t *,
 						       efi_physical_addr_t *,