4xx_pcie.c: Fix GCC 4.6 build warnings

4xx_pcie.c: Fix GCC 4.6 build warnings

Fix:
4xx_pcie.c: In function 'pcie_read_config':
4xx_pcie.c:230:6: warning: variable 'address' set but not used [-Wunused-but-set-variable]
4xx_pcie.c: In function 'pcie_write_config':
4xx_pcie.c:290:6: warning: variable 'address' set but not used [-Wunused-but-set-variable]
4xx_pcie.c: In function 'ppc4xx_setup_pcie_rootpoint':
4xx_pcie.c:1066:17: warning: variable 'rmbase' set but not used [-Wunused-but-set-variable]

Signed-off-by: Stefan Roese <sr@denx.de>