use struct kernfs_node instead of struct sysfs_dirent

for kernels >= 3.14.0

read:
commit 324a56e16e44baecac3ca799fd216154145c14bf
commit 024f647117d697165aaadf3f1af1343b7000149a
mpss-modules-3.2.1 untested but compiles fine on linux-3.14.1