arch/boardctl: Add printing board reset caller pid.

To check who called to reset the board, add outputting the pid running the boardctl.

And, Since, before the log is completely printed out, the board is rebooted, so the log does not print out.
So, Add  a delay of 100ms until the UART FIFO is completely empty.

Signed-off-by: eunwoo.nam <[email protected]>

os/arch/boardctl.c

@@ -62,6 +62,7 @@
 #include <stdint.h>
 #include <errno.h>
 #include <assert.h>
+#include <unistd.h>
 
 #include <tinyara/board.h>
 #include <tinyara/arch.h>
@@ -150,7 +151,9 @@ int boardctl(unsigned int cmd, uintptr_t arg)
 		sched_lock();
 		/* Add 100ms delay for flushing another logs like printf. */
 		up_mdelay(100);
-		lldbg("Board will Reboot now.\n");
+		lldbg("Board will Reboot now. pid: %d\n", getpid());
+		/* Add 100ms delay for flushing UART FIFO. */
+		up_mdelay(100);
 		ret = board_reset((int)arg);
 		break;
 #endif