fdisk: cleanup warnings

fdisk: cleanup warnings

* don't print:

	The number of cylinders for this disk is set to 12161.
	There is nothing wrong with that, but this is larger than 1024,
	and could in certain setups cause problems with:
	1) software that runs at boot time (e.g., old versions of LILO)
	2) booting and partitioning software from other OSs
	   (e.g., DOS FDISK, OS/2 FDISK)

  we really don't care about MS-DOS or extremely old LILO.

* inform users that DOS-compatible mode is bad and deprecated thing
  (It's difficult to use 2048 sectors grain or 4KiB sectors or
   alignment_offset in DOS mode where all is based on cylinders...)

* don't check for cylinders boundary in non-DOS mode

* inform about sector and I/O sizes

Signed-off-by: Karel Zak <kzak@redhat.com>