arm: enable unified assembly syntax in more files

This makes these files compileable, or in some cases less
broken, on Cortex-M targets.

In lcd-16bit.c, newer versions of GAS complain about the
infix condition codes so we use the suffix form instead,
which requires unified syntax to compile on GCC 4.9.

Change-Id: If45166d3fc83d64c692cbb331096a966397aa9e9

lib/rbcodec/codecs/libspeex/filters_arm4.S

@@ -33,6 +33,7 @@
 */
 
 #include "config.h"
+    .syntax unified
 #if CONFIG_CPU == PP5002
     .section .icode,"ax",%progbits
 #else