Fix SELECT_NETWORK freq parameter

Fix SELECT_NETWORK freq parameter

This functionality was originally added in commit
204c9ac4eed9f0ad69497f2efcd0d095dfd6e61c ('Extend select_network command
with freq= to reduce scan time') re-using wpa_s->manual_scan_freqs and
MANUAL_SCAN_REQ. That got broken when commit
35d403096eb63c787bd736dd8ba0902c34398fa8 ('Set NORMAL_SCAN_REQ on
SELECT_NETWORK/ENABLE_NETWORK') started overriding wpa_s->scan_req for
SELECT_NETWORK.

Fix this by adding a new scan frequency list specifically for
SELECT_NETWORK so that this does not need to depend on any specific
wpa_s->scan_req value.

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