LX60 carry 4 Mbyte FLASH and 128 Kbyte SRAM, LX200 carry 16 Mbyte FLASH
and 32 Mbyte SRAM. Either of these memories may be mapped to the system
ROM region.

Select boot from FLASH if -kernel option is not specified, otherwise
boot from SRAM.
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>