base: sync: Include seq_file.h in sync.h
sync.h uses struct seq_file in some function table prototypes. This
causes compile failures when including the header in files that do not
otherwise include seq_file.h
Signed-off-by: Jonathan Hamilton <jonathan.hamilton@imgtec.com>
[sw0312.kim: cherry-pick the commit
d37806bb7617 from https://android.googlesource.com/kernel/common to fix build warning]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I42183b09a64e26d57c5f176757f691378ffd578e