nimble/ll: Improve data packing in extended advertising report
nimble/ll: Improve data packing in extended advertising report

Without this patch, even having buffer of 257 octets for the HCI event, Nimble was
sending 253 octets of data plus 2 octets of header.
This patch fixes it.

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