[INET]: Fix incorrect "inet_sock->is_icsk" assignment.

The inet_create() and inet6_create() functions incorrectly set the
inet_sock->is_icsk field.  Both functions assume that the is_icsk field is
large enough to hold at least a INET_PROTOSW_ICSK value when it is actually
only a single bit.  This patch corrects the assignment by doing a boolean
comparison whose result will safely fit into a single bit field.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>