porting/linux: Fix ble_npl_time_delay implementation
porting/linux: Fix ble_npl_time_delay implementation

Previous implementation was inaccurate due to use
of sleep() function which uses seconds as a time parameter.

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