drm/lima: save process info for debug usage

When task fail, we can find its process with this information.

Tested-by: Andreas Baierl <[e-mail]>
Reviewed-by: Vasily Khoruzhick <[e-mail]>
Signed-off-by: Qiang Yu <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/lima/lima_ctx.c

···
 	if (err < 0)
 		goto err_out0;
 
+	ctx->pid = task_pid_nr(current);
+	get_task_comm(ctx->pname, current);
+
 	return 0;
 
 err_out0:

drivers/gpu/drm/lima/lima_ctx.h

···
 #define __LIMA_CTX_H__
 
 #include <linux/xarray.h>
+#include <linux/sched.h>
 
 #include "lima_device.h"
 
···
 	struct lima_device *dev;
 	struct lima_sched_context context[lima_pipe_num];
 	atomic_t guilty;
+
+	/* debug info */
+	char pname[TASK_COMM_LEN];
+	pid_t pid;
 };
 
 struct lima_ctx_mgr {