ide: make /proc/ide/ optional

All important information/features should be already available through
sysfs and ioctl interfaces.

Add CONFIG_IDE_PROC_FS (CONFIG_SCSI_PROC_FS rip-off) config option,
disabling it makes IDE driver ~5 kB smaller (on x86-32).

While at it add CONFIG_PROC_FS=n versions of proc_ide_{create,destroy}()
and remove no longer needed #ifdefs.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>