DMA speedtest build fix for genwait().

Apparently we forgot to update this example after the genwait()
signature change from Paul's thread polling PR, so it fails to build
currently on master.

I have taken the liberty of:
1) Removing the removed last argument from the genwait() call.
2) Adding a "make run" target, which I use frequently, just cuz I
   noticed it was missing.

Author: gyrovorbis

examples/dreamcast/basic/dma/speedtest/Makefile

@@ -16,5 +16,8 @@ clean: rm-elf
 rm-elf:
 	-rm -f $(TARGET)
 
+run: $(TARGET)
+	$(KOS_LOADER) $(TARGET)
+
 $(TARGET): $(OBJS)
 	kos-cc -o $@ $^

examples/dreamcast/basic/dma/speedtest/speedtest.c

@@ -93,7 +93,7 @@ do_dma_transfer(unsigned int test, pvr_ptr_t vram1, pvr_ptr_t vram2)
     }
 
     while ((volatile uint64_t)after == 0)
-        genwait_wait(&after, "IRQ wait", 0, NULL);
+        genwait_wait(&after, "IRQ wait", 0);
 
     return after - before;
 }