net: context: Skip reserved ports

The port numbers in the range from 0 to 1023 are the well-known ports
or system ports. Do not allocate them for users.

Change-Id: I4d7b4e1314759e4d8b260669946b9880282642c0
Signed-off-by: Ravi kumar Veeramally <ravikumar.veeramally@linux.intel.com>