nimble/ll: Fix enabling extended scan with no configuration
nimble/ll: Fix enabling extended scan with no configuration

Core Specification 5.3, Vol 4, Part E, 7.8.65:
"If Enable is set to 0x01 and the Host has not issued the
HCI_LE_Set_Extended_Scan_Parameters command, the Controller shall
either use vendor-specified parameters or return the error code
Command Disallowed (0x0C)"

To keep things simple we just reject in such case.

This was affecting HCI/DDI/BV-06-C qualification test case.

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble