uboot-imx

sbc8548: use proper PHY address

The values given for the PHY address were wrong, so the code
read no valid PHY ID, and fell through to the generic PHY
support, which would work on 1000M but would not auto negotiate
down to 100M or 10M.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>