gpu: nvgpu: rework ecc structure and sysfs

- create common file common/ecc.c which include common functions for add
  ecc counters and remove counters.
- common code will create a list of all counter which make it easier to
  iterate all counters.
- Add chip specific file for adding ecc counters.
- add linux specific file os/linux/ecc_sysfs.c to export counters to
  sysfs.
- remove obsolete code
- MISRA violation for using snprintf is not solved, tracking with
  jira NVGPU-859

Jira NVGPUT-115

Change-Id: I1905c43c5c9b2b131199807533dee8e63ddc12f4
Signed-off-by: Richard Zhao <rizhao@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1763536
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/posix/stubs.c

@@ -25,8 +25,19 @@
  * for an implementation.
  */
 
+#include <nvgpu/ecc.h>
+
 #include "gk20a/dbg_gpu_gk20a.h"
 
 void nvgpu_dbg_session_post_event(struct dbg_session_gk20a *dbg_s)
 {
 }
+
+int nvgpu_ecc_sysfs_init(struct gk20a *g)
+{
+	return 0;
+}
+
+void nvgpu_ecc_sysfs_remove(struct gk20a *g)
+{
+}