Inspection showed that gd->malloc_limit is zero. And it is because
generally SPL_FRAMEWORK initialize SPL's gd->malloc_limit. But when
SPL_FRAMEWORK is not enabled then in most cases nobody initialize
gd->malloc_limit and so SPL malloc simple does not work.
So disable SPL_SYS_MALLOC_SIMPLE by default when SPL_FRAMEWORK is not
enabled. SPL_SYS_MALLOC_SIMPLE can be disabled only by setting
SPL_SYS_MALLOC_F_LEN to zero. So do it.
This change fixes SPL error "alloc space exhausted" on P2020 board.