drivers/base/devtmpfs.c: don't pretend path is const in delete_path

path is the result of kstrdup, and we repeatedly call strrchr on it,
modifying it through the returned pointer. So there's no reason to
pretend path is const.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>