net: netcp: enclose macros in parentheses

Fix following checkpatch error. It seems to have passed checkpatch
last time when original code was introduced.

 ERROR: Macros with complex values should be enclosed in parentheses
 #172: FILE: drivers/net/ethernet/ti/netcp_ethss.c:869:
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: WingMan Kwok <w-kwok2@ti.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Mugunthan V N <mugunthanvnm@ti.com>
CC: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
CC: Grygorii Strashko <grygorii.strashko@ti.com>
CC: Christoph Jaeger <cj@linux.com>
CC: Lokesh Vutla <lokeshvutla@ti.com>
CC: Markus Pargmann <mpa@pengutronix.de>
CC: Kumar Gala <galak@codeaurora.org>
CC: Ian Campbell <ijc+devicetree@hellion.org.uk>
CC: Mark Rutland <mark.rutland@arm.com>
CC: Pawel Moll <pawel.moll@arm.com>
CC: Rob Herring <robh+dt@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>