net: qrtr: ns: Increase socket recvbuf

Increase the socket recvbuf for the ns so control packets are not
dropped in heavy traffic situations like ssr. This change will not
actually set the recvbuf to INT_MAX but to the system defined rmem_max
for sockets.

Change-Id: If56eac164a7ea3f0857170d3966c3c174a7460ae
Signed-off-by: Chris Lew <clew@codeaurora.org>