ftrace: Deal with error return code of the ftrace_process_locs() function

The ftrace_process_locs() function may return -ENOMEM error code, which
should be handled by the callers.

Link: https://lkml.kernel.org/r/20220120065949.1813231-1-ytcoode@gmail.com



Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>