MPC8308RDB: various clean ups

MPC8308RDB: various clean ups

This patch cleans up the Freescale MPC8308RDB Development board support.
Things fixed:
 - Removed unused PCIE2 definitions from configuration
 - SICR{L,H} defines used for System I/O Configuration Registers values
   instead of hardcoding
 - CONFIG_SYS_SCCR_PCIEXP1CM used to enable PCIE clock instead of
   writing to SCCR from the board code
 - sleep mode stuff removed as MPC8308 has no support for deep sleep and
   PMCCR1 register. board_early_init_f() removed.
 - MPC8308 has no ERRATA for DDR controller so workaround removed
 - 'assignment in if statement' issues solved
 - use LBLAWAR_* defines instead of hardcoding

Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>