nl80211: Add support for multiple scan plans for scheduled scan

nl80211: Add support for multiple scan plans for scheduled scan

Add 'scan plans' to driver scan parameters for scheduled scan.
Each 'scan plan' specifies the number of iterations to run the scan
request and the interval between iterations. When a scan plan
finishes (i.e., it was run for the specified number of iterations),
the next scan plan is executed. The last scan plan will run
infinitely.

The maximum number of supported scan plans, the maximum number of
iterations for a single scan plan and the maximum scan interval
are advertised by the driver.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>