sparc64: Implement HAVE_CONTEXT_TRACKING

Mark the places when the system are in user or are in kernel.
This is used to make full dynticks system (tickless) --
CONFIG_NO_HZ_FULL dependence.

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>