[SPARC64]: Fix bogus flush instruction usage.

Some of the trap code was still assuming that alternate
global %g6 was hard coded with current_thread_info().
Let's just consistently flush at KERNBASE when we need
a pipeline synchronization.  That's locked into the TLB
and will always work.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc64/kernel/winfixup.S b/arch/sparc64/kernel/winfixup.S
index de58803..c0545d0 100644
--- a/arch/sparc64/kernel/winfixup.S
+++ b/arch/sparc64/kernel/winfixup.S
@@ -20,7 +20,8 @@
 	ldx	[%l1 + %lo(sparc64_kern_pri_context)], %l1
 	mov	PRIMARY_CONTEXT, %g1
 	stxa	%l1, [%g1] ASI_DMMU
-	flush	%g6
+	sethi	%hi(KERNBASE), %l1
+	flush	%l1
 	retl
 	 nop