tcp: don't mask EOF and socket errors on nonblocking splice receive

[ Upstream commit: 4f7d54f59bc470f0aaa932f747a95232d7ebf8b1 ]

Currently, setting SPLICE_F_NONBLOCK on splice from a TCP socket
results in masking of EOF (RDHUP) and error conditions on the socket
by an -EAGAIN return.  Move the NONBLOCK check in tcp_splice_read()
to be after the EOF and error checks to fix this.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>