staging: rtl8723bs: clean up memcpy() in rtw_check_bcn_info

staging: rtl8723bs: clean up memcpy() in rtw_check_bcn_info

Move the ssid memcpy() inside the ie null-check to avoid calling it
with a NULL-derived pointer (p + 2) when the ie is missing.

While the kernel handles 0-length memcpy() safely as a no-op, keeping
the call outside the check is confusing and poor practice. This
change improves code readability.

Signed-off-by: Luka Gejak <luka.gejak@linux.dev>
Reviewed-by: Dan Carpenter <error27@gmail.com>
Link: https://patch.msgid.link/20260415085638.6427-1-luka.gejak@linux.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>