ANDROID: initramfs: call free_initrd() when skipping init

Memory allocated for initrd would not be reclaimed if initializing ramfs
was skipped.

Bug: 69681565
Bug: 69901741
Test: "grep MemTotal /proc/meminfo" increases by a few MB on an Android
device with a/b boot.

Change-Id: Ifbe094d303ed12cfd6de6aa004a8a19137a2f58a
Signed-off-by: Nick Bray <ncbray@google.com>
(cherry picked from commit f26d3c76d3)

init/initramfs.c

@@ -622,8 +622,11 @@ static int __init populate_rootfs(void)
 {
 	char *err;
 
-	if (do_skip_initramfs)
+	if (do_skip_initramfs) {
+		if (initrd_start)
+			free_initrd();
 		return default_rootfs();
+	}
 
 	err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
 	if (err)