[SPARC64]: Fix return from trap on SUN4V.

We need to set the global register set _AND_ disable
PSTATE_IE in %pstate.  The original patch sequence was
leaving PSTATE_IE enabled when returning to kernel mode,
oops.

This fixes the random register corruption being seen
on SUN4V.

Signed-off-by: David S. Miller <davem@davemloft.net>