drm: fix sparse warnings on undeclared symbols in crc debugfs

Fixes sparse warnings:

drivers/gpu/drm/drm_debugfs_crc.c:118:30: warning: symbol
'drm_crtc_crc_control_fops' was not declared. Should it be static?

drivers/gpu/drm/drm_debugfs_crc.c:264:30: warning: symbol
'drm_crtc_crc_data_fops' was not declared. Should it be static?

drivers/gpu/drm/drm_debugfs_crc.c:281:5: warning: symbol
'drm_debugfs_crtc_crc_add' was not declared. Should it be static?

Fixes: 9edbf1fa60 ("drm: Add API for capturing frame CRCs")
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Emil Velikov <emil.velikov@collabora.com>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1476790115-28665-1-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/drm_debugfs_crc.c

@@ -30,6 +30,7 @@
 #include <linux/ctype.h>
 #include <linux/debugfs.h>
 #include <drm/drmP.h>
+#include "drm_internal.h"
 
 /**
  * DOC: CRC ABI
@@ -115,7 +116,7 @@ static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
 	return len;
 }
 
-const struct file_operations drm_crtc_crc_control_fops = {
+static const struct file_operations drm_crtc_crc_control_fops = {
 	.owner = THIS_MODULE,
 	.open = crc_control_open,
 	.read = seq_read,
@@ -261,7 +262,7 @@ static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
 	return LINE_LEN(crc->values_cnt);
 }
 
-const struct file_operations drm_crtc_crc_data_fops = {
+static const struct file_operations drm_crtc_crc_data_fops = {
 	.owner = THIS_MODULE,
 	.open = crtc_crc_open,
 	.read = crtc_crc_read,