flash_clear_pgperr_flag is a name used on f247, which is actually most analogous to the SIZERR bit on l4, (it's a parallelism error) the bit being cleared originally in this function, PROGERR is a new bit, and should have it's own name. Add a function to handle the previously unhandled size/parallelism flag, and rename the existing one to properly reflect it's new name.