net: Rename net_nbuf_write to net_nbuf_append

Current net_nbuf_write() api just appends data to last fragment. And
doesn't write data based on offset. That's why renaming this api.

New net_nbuf_write() apis based on offset will be coming soon.

Change-Id: Ie8e13e5f6091a279b62b6d8b0b3928a5187e75b0
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: Ravi kumar Veeramally <ravikumar.veeramally@linux.intel.com>
7 files changed