[MTD] sysfs support should not depend on CONFIG_PROC_FS

Move the driver model init code out of the "#ifdef CONFIG_PROC_FS"
block.

Tested with both values of CONFIG_PROC_FS .  Tested with CONFIG_MTD=m .

Issue was reported here: http://lkml.org/lkml/2009/4/4/107

Signed-off-by: Kevin Cernekee <kpc.mtd@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>