malloc: Add 'malloc' command with 'info' subcommand

Add a command to display malloc heap statistics, showing total heap
size and memory currently in use.

Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>

test/cmd/malloc.c

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Test for 'malloc' command
+ *
+ * Copyright 2025 Canonical Ltd
+ * Written by Simon Glass <simon.glass@canonical.com>
+ */
+
+#include <malloc.h>
+#include <dm/test.h>
+#include <test/cmd.h>
+#include <test/ut.h>
+
+/* Test 'malloc info' command */
+static int cmd_test_malloc_info(struct unit_test_state *uts)
+{
+	struct malloc_info info;
+
+	ut_assertok(malloc_get_info(&info));
+	ut_assert(info.total_bytes >= CONFIG_SYS_MALLOC_LEN);
+	ut_assert(info.in_use_bytes < info.total_bytes);
+
+	ut_assertok(run_command("malloc info", 0));
+	ut_assert_nextlinen("total bytes   = ");
+	ut_assert_nextlinen("in use bytes  = ");
+	ut_assert_console_end();
+
+	return 0;
+}
+CMD_TEST(cmd_test_malloc_info, UTF_CONSOLE);