As per the discussion in #15331, fixed issue where stm32h7 chips
use hardware ECC bits in program memory that disallow overwriting
32-byte flash line that has already been written. As such,
this change allows for a variant implementation of the flashfs system
that uses more space in the flash entry header in order to
allow an entire line to be reserved for erasing an entry.
Signed-off-by: Taylor Nelms <tnelms@roboticresearch.com>
