update f2 and f4 option read/write code routines

1) no need to unlock option flash to read it.

"The option byte are always read-accessible and write-protected by default."

current device specific option read code now only differs from generic read code
by reading option bytes in the flash option byte register instead of option base.

2) f4 and f2 have similar registers : use the same write code, with flash/option lock
helpers. add flash busy wait and relock at end of access.

3) add f446 option info to chip id