sparc64: Do not clobber %g2 in xcall_fetch_glob_regs().

%g2 is meant to hold the CPUID number throughout this routine, since
at the very beginning, and at the very end, we use %g2 to calculate
indexes into per-cpu arrays.

However we erroneously clobber it in order to hold the %cwp register
value mid-stream.

Fix this code to use %g3 for the %cwp read and related calulcations
instead.
Reported-by: NMeelis Roos <mroos@linux.ee>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/kernel/central.c

@@ -269,4 +269,4 @@ static int __init sunfire_init(void)
 	return 0;
 }
 
-subsys_initcall(sunfire_init);
+fs_initcall(sunfire_init);

arch/sparc/mm/ultra.S

@@ -495,11 +495,11 @@ xcall_fetch_glob_regs:
 	stx		%o7, [%g1 + GR_SNAP_O7]
 	stx		%i7, [%g1 + GR_SNAP_I7]
 	/* Don't try this at home kids... */
-	rdpr		%cwp, %g2
-	sub		%g2, 1, %g7
+	rdpr		%cwp, %g3
+	sub		%g3, 1, %g7
 	wrpr		%g7, %cwp
 	mov		%i7, %g7
-	wrpr		%g2, %cwp
+	wrpr		%g3, %cwp
 	stx		%g7, [%g1 + GR_SNAP_RPC]
 	sethi		%hi(trap_block), %g7
 	or		%g7, %lo(trap_block), %g7