cfi_flash: Break long lines

This patch tries to keep all lines in the cfi_flash driver below 80
columns. There are a few lines left which don't fit this requirement
because I couldn't find any trivial way to break them (i.e. it would
take some restructuring, which I intend to do in a later patch.)
Signed-off-by: NHaavard Skinnemoen <hskinnemoen@atmel.com>