efi_client: Support running an app

Add support for running another app from with the EFI app. This can be
used to boot an OS, for example.

Signed-off-by: Simon Glass <sjg@chromium.org>

lib/efi/run.c

@@ -129,9 +129,6 @@ efi_status_t efi_bootflow_run(struct bootflow *bflow)
 		fdt = map_sysmem(bflow->fdt_addr, 0);
 	}
 
-	if (IS_ENABLED(CONFIG_EFI_APP))
-		return EFI_UNSUPPORTED;
-
 	ret = efi_binary_run_dp(bflow->buf, bflow->size, fdt, NULL, 0, device,
 				image);