nimble/controller: Fix LE Test End Command return value
nimble/controller: Fix LE Test End Command return value

From Core Specification:
"This command is used to stop any test which is in progress. The
Number_Of_Packets for a transmitter test shall be reported as 0x0000.
The Number_Of_Packets is an unsigned number and contains the number of
received packets."

X-Original-Commit: 96127812aa2db70e9790519a28efdad4dc145deb

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