fs/proc/generic.c: switch to ida_simple_get/remove

The code can be much simplified by switching to ida_simple_get/remove.

Link: http://lkml.kernel.org/r/8d1cc9f7-5115-c9dc-028e-c0770b6bfe1f@gmail.com


Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>