drivers: flash: w25q: erase operations must be erase-size aligned

 - Erase operations must be aligned to the erase-size.
 - Don't need to perform an alignment check on a full erase. The offset
   is not used in this case.
 - Don't need to perform alignment check on a sector sized erase, as
   this alignment is checked on entrance to the function.
 - Removed some whitespace.

Signed-off-by: Ryan C Johnson <ryan.johnson@flex.com>