cmd: in do_efi_capsule_esrt use efi_get_configuration_table

Use library function efi_get_configuration_table() to find the ESRT.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/cmd/efidebug.c b/cmd/efidebug.c
index a3a7556..a587860 100644
--- a/cmd/efidebug.c
+++ b/cmd/efidebug.c
@@ -173,15 +173,12 @@
 static int do_efi_capsule_esrt(struct cmd_tbl *cmdtp, int flag,
 			       int argc, char * const argv[])
 {
-	struct efi_system_resource_table *esrt = NULL;
+	struct efi_system_resource_table *esrt;
 
 	if (argc != 1)
 		return CMD_RET_USAGE;
 
-	for (int idx = 0; idx < systab.nr_tables; idx++)
-		if (!guidcmp(&efi_esrt_guid, &systab.tables[idx].guid))
-			esrt = (struct efi_system_resource_table *)systab.tables[idx].table;
-
+	esrt = efi_get_configuration_table(&efi_esrt_guid);
 	if (!esrt) {
 		log_info("ESRT: table not present\n");
 		return CMD_RET_SUCCESS;