[mips] Resolve issue with .align directive, when using clang IAS

Clang IAS does not support .align without args, concrete value is needed.

Change-Id: I50e20c374b8e88966310c0c9e6cc41eea054eb32
diff --git a/libpixelflinger/col32cb16blend.S b/libpixelflinger/col32cb16blend.S
index 1831255..721fd7d 100644
--- a/libpixelflinger/col32cb16blend.S
+++ b/libpixelflinger/col32cb16blend.S
@@ -16,7 +16,7 @@
  */
 
     .text
-    .align
+    .align 4
 
     .global scanline_col32cb16blend_arm