MIPS: Use CONFIG_CPU_MIPSR2 in csum_partial.S

The csum_partial implementation contain optimalizations for the MIPS R2
instruction set. This optimization is never enabled however because the
if directive uses the CPU_MIPSR2 constant which is not defined anywhere.

Use the CONFIG_CPU_MIPSR2 constant instead.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4971/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/lib/csum_partial.S b/arch/mips/lib/csum_partial.S
index 507147a..a6adffb 100644
--- a/arch/mips/lib/csum_partial.S
+++ b/arch/mips/lib/csum_partial.S
@@ -270,7 +270,7 @@
 #endif
 
 	/* odd buffer alignment? */
-#ifdef CPU_MIPSR2
+#ifdef CONFIG_CPU_MIPSR2
 	wsbh	v1, sum
 	movn	sum, v1, t7
 #else
@@ -670,7 +670,7 @@
 	addu	sum, v1
 #endif
 
-#ifdef CPU_MIPSR2
+#ifdef CONFIG_CPU_MIPSR2
 	wsbh	v1, sum
 	movn	sum, v1, odd
 #else