- Current implementation requires that memory size is configured using
  PHYS_SDRAM and PHYS_SDRAM_2 settings depending on actual memory
  size in the board config file. As PHYS_SDRAM_2 memory area is not
  used if total memory size is < 3 GiB, cache and MMU setup would use
  wrong values when initialized. Thus, dynamic initialization of 4 GiB
  and 2 GiB modules is not possible with one single bootloader binary.
- Add support to determine actual memory size using the
  'board_phys_sdram_size' function and calculate size of DRAM1 and
  DRAM2 regions accordingly. Fix cache enable setup to use detected size
  of memory areas instead of fixed config values.
- Ensure that memory regions are set up properly even if OPTEE memory
  region splits DRAM1 into multiple regions.

Signed-off-by: Thomas Schaefer <thomas.schaefer@kontron.com>