Modify gPXE core and drivers to work with the new timer subsystem

Signed-off-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>

src/hci/mucurses/kb.c

@@ -1,6 +1,6 @@
 #include <curses.h>
 #include <stddef.h>
-#include <timer.h>
+#include <unistd.h>
 #include "mucurses.h"
 
 /** @file