vold: fix warnings for 64-bit

Replace MINOR(dev_t) and MAJOR(dev_t) with minor and major,
which cast to int.
Cast int to uintptr_t before casting to pointer

Change-Id: I59375518f15d27f400fcd4f8a8dfe5ebdd8350e6
diff --git a/fstrim.c b/fstrim.c
index 73705f9..2bd0577 100644
--- a/fstrim.c
+++ b/fstrim.c
@@ -116,7 +116,7 @@
     /* Release the wakelock that let us work */
     release_wake_lock(FSTRIM_WAKELOCK);
 
-    return (void *)ret;
+    return (void *)(uintptr_t)ret;
 }
 
 int fstrim_filesystems(void)