sky2: fix management of driver LED

Observed by Mike McCormack.

The LED bit here is just a software controlled value used to
turn on one of the LED's on some boards. The register value was wrong,
which could have been causing some power control issues.
Get rid of problematic define use the correct mask.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>