floppy: replace NO_GEOM macro with a function

This patch replaces the NO_GEOM macro with a proper static inline function and
converts an open-coded caller in check_floppy_change() to use it.

Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>