mtd: cfi_flash: fix indentation

The indentation is misleading here and suggests that the write command
will be only executed in the else clause.
It seems like this is not intended, so fix the indentation to avoid
both compiler warnings and puzzled readers.

Pointed out by GCC 6.2's -Wmisleading-indentation warning.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Stefan Roese <sr@denx.de>