UBSan: Fix RRM beacon processing attempt without scan_info

UBSan: Fix RRM beacon processing attempt without scan_info

Some driver interfaces (e.g., wext) might not include the
data->scan_info information and data could be NULL here. Do not try to
call the RRM handler in this case since that would dereference the NULL
pointer when determining where scan_info is located and could
potentially result in trying to read from unexpected location if RRM is
enabled with a driver interface that does not support it.

events.c:1907:59: runtime error: member access within null pointer of type 'union wpa_event_data'

Signed-off-by: Jouni Malinen <j@w1.fi>