sparc64: optimize functions that access tick

sparc64: optimize functions that access tick

Replace read tick function pointers with the new hot-patched get_tick().
This optimizes the performance of functions such as: sched_clock()

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Orabug: 24401250
Orabug: 25637776

(cherry picked from commit eae3fc9871111e9bbc77dad5481a3e805e02ac46)
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>