fs/proc/Kconfig: fix indentation

Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
        $ sed -e 's/^        /	/' -i */Kconfig

[adobriyan@gmail.com: add two spaces where necessary]
Link: http://lkml.kernel.org/r/20191124133936.GA5655@avx2


Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>