mx25pdk: Remove lowlevel_init.S file

As the lowlevel_init function is empty we should better
remove this assembly file entirely and use a dummy C
function instead.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>

board/freescale/mx25pdk/Makefile

@@ -7,4 +7,3 @@
 #
 
 obj-y	:= mx25pdk.o
-obj-y	+= lowlevel_init.o

board/freescale/mx25pdk/lowlevel_init.S

@@ -1,10 +0,0 @@
-/*
- * Copyright (c) 2011  Freescale Semiconductor
- *
- * SPDX-License-Identifier:	GPL-2.0+
- */
-
-.globl lowlevel_init
-lowlevel_init:
-
-	mov	pc, lr

board/freescale/mx25pdk/mx25pdk.c

@@ -186,3 +186,6 @@ int checkboard(void)
 
 	return 0;
 }
+
+/* Lowlevel init isn't used on mx25pdk, so just provide a dummy one here */
+void lowlevel_init(void) {}