fs: ufs: use ktime_get_real_ts64() for birthtime

CURRENT_TIME is not y2038 safe.  Replace it with ktime_get_real_ts64().
Inode time formats are already 64 bit long and accommodates time64_t.

Link: http://lkml.kernel.org/r/1491613030-11599-6-git-send-email-deepa.kernel@gmail.com


Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>