sparc64: Delete now unused user copy fixup functions.

[ Upstream commit 0fd0ff01 ]

Now that all of the user copy routines are converted to return
accurate residual lengths when an exception occurs, we no longer need
the broken fixup routines.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>