* Adds target tms570-launchpad, for TI TMS570 Launchpad Dev Kit
(https://www.ti.com/store/ti/en/p/product/?p=LAUNCHXL2-TMS57012)
* Adds CPU definitions for Cortex R4F (BE) CPU, implementing
ARMv7-R ISA. Does not yet add definitions for ARMv7 arch entry
functions.
* Board does not yet build - platform.c/uart.c are empty, no GIC
entry points provided.