[PATCH] selinux: simplify sel_read_bool

Simplify sel_read_bool to use the simple_read_from_buffer helper, like the
other selinuxfs functions.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>