stm32: f4: flash: support extended sector ranges

F42xx and F43xx have extended sector ranges.

Reported-by: H2OBrain@irc
stm32: f24: flash: Make code match documentation

This removes the shift from the defines, and includes them in the helper
function, making the code match the documentation, and following how the
rest of the library commonly operates.

Code using the existing defines should continue to work.