bsps: Move benchmark timer to bsps

This patch is a part of the BSP source reorganization.

Update #3285.

bsps/m68k/av5282/btimer/btimer.c

@@ -0,0 +1,34 @@
+/*
+ *  Timer Init
+ *
+ *  Use the last DMA timer (DTIM3) as the diagnostic timer.
+ */
+
+#include <rtems.h>
+#include <rtems/btimer.h>
+#include <bsp.h>
+
+void
+benchmark_timer_initialize(void)
+{
+    int preScaleDivisor = 58;
+    int div = MCF5282_TIMER_DTMR_CLK_DIV1;
+    MCF5282_TIMER3_DTRR = 0x2710;
+    MCF5282_TIMER3_DTMR = 0;
+    MCF5282_TIMER3_DTMR = MCF5282_TIMER_DTMR_PS(preScaleDivisor - 1) | div |
+                          MCF5282_TIMER_DTMR_RST;
+}
+
+/*
+ * Return timer value in microsecond units
+ */
+uint32_t
+benchmark_timer_read(void)
+{
+    return MCF5282_TIMER3_DTCN;
+}
+
+void
+benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
+{
+}