kprobes: Remove unnecessary ‘NULL’ values from correct_ret_addr

The 'correct_ret_addr' pointer is always set in the later code, no need
to initialize it at definition time.

Link: https://lore.kernel.org/all/20230704194359.3124-1-zeming@nfschina.com/



Signed-off-by: Li zeming <zeming@nfschina.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>