msm: kgsl: fix build issue with devfreq_trace.h

When building the kernel in tree we get:

In file included from drivers/devfreq/devfreq_trace.h:43:0,
                 from drivers/devfreq/devfreq_trace.c:20:
include/trace/define_trace.h:79:43: fatal error: ./devfreq_trace.h:
No such file or directory
 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)

The recommend solution is to add the include path to CFLAGS for the file.

Change-Id: I0389abcdcec29b35fa4da997b4ee3fd71c8a6c04
Signed-off-by: Kumar Gala <galak@codeaurora.org>