Enable CONFIG_SPL_DM and CONFIG_SPL_SERIAL_SUPPORT, which provide
Driver Model UART support on SPL.
CONFIG_SYS_SPL_MALLOC_{START,SIZE} should be dropped because simple
malloc is preferred on SPL. Dlmalloc requires some static variables
on .data section that is not available yet for NOR boot mode etc.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
499785b970