tracing: Avoid -Warray-bounds warning for __rel_loc macro

tracing: Avoid -Warray-bounds warning for __rel_loc macro

Since -Warray-bounds checks the destination size from the type of given
pointer, __assign_rel_str() macro gets warned because it passes the
pointer to the 'u32' field instead of 'trace_event_raw_*' data structure.
Pass the data address calculated from the 'trace_event_raw_*' instead of
'u32' __rel_loc field.

Link: https://lkml.kernel.org/r/20220125233154.dac280ed36944c0c2fe6f3ac@kernel.org
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[ This did not fix the warning, but is still a nice clean up ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>