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/tests/kms_psr_sink_crc.c b/tests/kms_psr_sink_crc.c
index 8f6bdc0..f66a754 100644
--- a/tests/kms_psr_sink_crc.c
+++ b/tests/kms_psr_sink_crc.c
@@ -195,7 +195,7 @@
 {
 	char buf[512];
 
-	igt_debugfs_read("i915_edp_psr_status", buf);
+	igt_debugfs_read(data->drm_fd, "i915_edp_psr_status", buf);
 
 	return running_with_psr_disabled ||
 		strstr(buf, "Sink_Support: yes\n");
@@ -205,7 +205,7 @@
 {
 	char buf[512];
 
-	igt_debugfs_read("i915_edp_psr_status", buf);
+	igt_debugfs_read(data->drm_fd, "i915_edp_psr_status", buf);
 
 	return running_with_psr_disabled ||
 		strstr(buf, "HW Enabled & Active bit: yes\n");
@@ -229,7 +229,7 @@
 	if (igt_interactive_debug)
 		return;
 
-	file = igt_debugfs_fopen("i915_sink_crc_eDP1", "r");
+	file = igt_debugfs_fopen(data->drm_fd, "i915_sink_crc_eDP1", "r");
 	igt_require(file);
 
 	ret = fscanf(file, "%s\n", crc);