Rename 'platform.h' in 'imx6ul' and 'qemu-vexpress-a9' BSPs.

This filename conflicts with the 'mbedtls' package. They are renamed
in the name of the corresponding chips and included in 'board.h'.
Files that rely on this file should include 'board.h' instead.

libcpu/arm/cortex-a/gic.h

@@ -12,7 +12,7 @@
 #define __GIC_H__
 
 #include <rthw.h>
-#include <platform.h>
+#include <board.h>
 
 int arm_gic_dist_init(rt_uint32_t index, rt_uint32_t dist_base, int irq_start);
 int arm_gic_cpu_init(rt_uint32_t index, rt_uint32_t cpu_base);

libcpu/arm/cortex-a/interrupt.h

@@ -12,7 +12,7 @@
 #define __INTERRUPT_H__
 
 #include <rthw.h>
-#include <platform.h>
+#include <board.h>
 
 #define INT_IRQ     0x00
 #define INT_FIQ     0x01

libcpu/arm/cortex-a/trap.c

@@ -10,7 +10,7 @@
 
 #include <rtthread.h>
 #include <rthw.h>
-#include <platform.h>
+#include <board.h>
 
 #include "armv7.h"
 #include "interrupt.h"