boards: riscv: Add initial support for titanium_ti60_f225

This FPGA board can be loaded with a RISC-V core and utilized
with Zephyr.

Product link:
https://www.efinixinc.com/products-devkits-titaniumti60f225.html



Signed-off-by: Manojkumar Subramaniam <manoj@electrolance.com>