MIPS: Fixup check for invalid scratch register

The invalid value for scratch register is -1, so update the checks of
the form (scratch_reg > 0) to be (scratch_reg >= 0).  This will fix
the case in Netlogic XLP where the scratch_reg can be 0.
Signed-off-by: NJayachandran C <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5444/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/mm/tlbex.c

@@ -345,7 +345,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 	int smp_processor_id_sel;
 	int smp_processor_id_shift;
 
-	if (scratch_reg > 0) {
+	if (scratch_reg >= 0) {
 		/* Save in CPU local C0_KScratch? */
 		UASM_i_MTC0(p, 1, c0_kscratch(), scratch_reg);
 		r.r1 = K0;
@@ -395,7 +395,7 @@ static struct work_registers __cpuinit build_get_work_registers(u32 **p)
 
 static void __cpuinit build_restore_work_registers(u32 **p)
 {
-	if (scratch_reg > 0) {
+	if (scratch_reg >= 0) {
 		UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 		return;
 	}
@@ -684,7 +684,7 @@ static __cpuinit void build_restore_pagemask(u32 **p,
 			uasm_i_mtc0(p, 0, C0_PAGEMASK);
 			uasm_il_b(p, r, lid);
 		}
-		if (scratch_reg > 0)
+		if (scratch_reg >= 0)
 			UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 		else
 			UASM_i_LW(p, 1, scratchpad_offset(0), 0);
@@ -940,7 +940,7 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		uasm_i_jr(p, ptr);
 
 		if (mode == refill_scratch) {
-			if (scratch_reg > 0)
+			if (scratch_reg >= 0)
 				UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
 			else
 				UASM_i_LW(p, 1, scratchpad_offset(0), 0);
@@ -1297,7 +1297,7 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
 	memset(relocs, 0, sizeof(relocs));
 	memset(final_handler, 0, sizeof(final_handler));
 
-	if ((scratch_reg > 0 || scratchpad_available()) && use_bbit_insns()) {
+	if ((scratch_reg >= 0 || scratchpad_available()) && use_bbit_insns()) {
 		htlb_info = build_fast_tlb_refill_handler(&p, &l, &r, K0, K1,
 							  scratch_reg);
 		vmalloc_mode = refill_scratch;