proc-misc code is noticeably full of "if (de)" checks when PDE passed is
always valid.  Remove them.

Addition of such check in proc_lookup_de() is for failed lookup case.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>