86xx: Fix renamed GUR symbols in sbc8641d board.

Back in commit a551cee9
(86xx: Fix GUR PCI config registers properly), we should have
changed the MPC86xx_PORBMSR_HA and MPC86xx_PORDEVSR_IO_SEL
symbols in the sbc8641d board as well.  Fix this oversight.

Signed-off-by: Jon Loeliger <jdl@freescale.com>