ppc4xx: Update AMCC Bamboo 440EP support

Changed storage type of cfg_simulate_spd_eeprom to const
Changed storage type of gpio_tab to stack storage
(Cannot access global data declarations in .bss until afer code relocation)

Improved SDRAM tests to catch problems where data is not uniquely addressable
(e.g. incorrectly programmed SDRAM row or columns)

Added CONFIG_PROG_SDRAM_TLB to support Bamboo SIMM/DIMM modules
Fixed AM29LV320DT (OpCode Flash) sector map

Signed-off-by: Eugene OBrien <eugene.obrien@advantechamt.com>
Signed-off-by: Stefan Roese <sr@denx.de>