bsp/hifive1: Add config and reboot fcb
bsp/hifive1: Add config and reboot fcb

Flash areas were already configured in bsp but
two syscfg values were missing to be able to
use reboot log and config fcb as in other platforms.

mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core