Socket: Added variable to take return value of read() in 'tcp_autocorking()' function

Added a variable to accept the return value of read() in line 266 in function 'mk_socket_tcp_autocorking()'. This patch removes the following warning that arises during 'make' :

--------------- WARNING --------------------
mk_socket.c: In function ‘mk_socket_tcp_autocorking’:
mk_socket.c:265:9: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result]
--------------- WARNING --------------------

Signed-off-by: Savita TS <savita.seetaraman5@gmail.com>