adfs: use timespec64 for time conversion

We just truncate the seconds to 32-bit in one place now, so this can
trivially be converted over to using timespec64 consistently.

Link: http://lkml.kernel.org/r/20180620100133.4035614-1-arnd@arndb.de


Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>