Rollback firmware flashing in case iinternal flash error (brick rollback in case bootblock region being WP)

[tlaurion]

flasrom/flashprog could fail internal flashing.

A simple protection against this would be to
1- backup the current rom in memory
2- do whatever we currently do in flash.sh || flash backup rom in case of error

Be safer against possible user errors with chip specific SPI WP support landing iteratively under flashrom/flashprog and user interest into WP.