Number of channels is stored in a separate macro
in a header file and channel list is constructed
independently. The macro is used to define survey
array.

This fixes a recent regression introduced after
adding support for 144 channel. The regression
would lead to a warning and incomplete survey data
on channel 165:

  chan info: invalid frequency 5825 (idx 38 out of bounds)

Also make sure to enforce the sizes and avoid this
kind of problem in the future.

Fixes: 4a7898fe

 ("ath10k: enable channel 144 on 5GHz band")
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>