mpc83xx: fix pcie configuration space read/write

This patch fix a problem for the pcie enumeration when the mpc83xx
pcie controller is connected with switch or we use both of the two
pcie controller.

Signed-off-by: Leo Liu <liucai.lfn@gmail.com>

fix codingstyle and compiler warning: 'pcie_priv' defined but not used

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>