Restore "lib: Open debugfs files for the given DRM device"

This reverts commit 25fbae15262cf570e207e62f50e7c5233e06bc67, restoring
commit 301ad44cdf1b868b1ab89096721da91fa8541fdc
Author: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Date:   Thu Mar 2 10:37:11 2017 +0100

    lib: Open debugfs files for the given DRM device

with fixes.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/lib/igt_gt.h b/lib/igt_gt.h
index e44b6db..1ed833d 100644
--- a/lib/igt_gt.h
+++ b/lib/igt_gt.h
@@ -51,12 +51,12 @@
 igt_hang_t igt_hang_ring(int fd, int ring);
 void igt_post_hang_ring(int fd, igt_hang_t arg);
 
-void igt_force_gpu_reset(void);
+void igt_force_gpu_reset(int fd);
 
 void igt_fork_hang_helper(void);
 void igt_stop_hang_helper(void);
 
-int igt_open_forcewake_handle(void);
+int igt_open_forcewake_handle(int fd);
 
 int igt_setup_clflush(void);
 void igt_clflush_range(void *addr, int size);