sfp: fix RX_LOS signal handling

[ Upstream commit acf1c02f023926b8b04672a9e81b1711ae681619 ]

The options word is a be16 quantity, so we need to test the flags
having converted the endian-ness.  Convert the flag bits to be16,
which can be optimised by the compiler, rather than converting a
variable at runtime.

Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>