scb9328: Add ARM relocation support

This patch fixes compiler errors due to missing definitions of
CONFIG_SYS_SDRAM_BASE and CONFIG_SYS_INIT_SP_ADDR.

It also does some cleanup: CONFIG_SYS_TEXT_BASE was moved to scb9328.h,
obsolete config.mk was removed. The scb9328 board has 1 DRAM bank, so don't
ask for more banks. CONFIG_NR_DRAM_BANKS will ever be 1.

Signed-off-by: Torsten Koschorrek <koschorrek@synertronixx.de>