Makefile support for doc target.

Builds uapi documentation in html format using doxygen.
See doc/sof_uapi/html/index.html
First dox samples in the source code provided by the patch.

Signed-off-by: Marcin Maka <marcin.maka@linux.intel.com>
diff --git a/doc/sof_uapi.doxygen.in b/doc/sof_uapi.doxygen.in
new file mode 100644
index 0000000..74052f1
--- /dev/null
+++ b/doc/sof_uapi.doxygen.in
@@ -0,0 +1,33 @@
+PROJECT_NAME     = "Sound Open Firmware"
+OUTPUT_DIRECTORY = sof_uapi
+GENERATE_LATEX   = NO
+GENERATE_RTF	 = NO
+GENERATE_MAN     = NO
+GENERATE_XML	 = YES
+
+CASE_SENSE_NAMES = NO
+INPUT            = @top_srcdir@/src/include/uapi
+EXCLUDE		 =
+RECURSIVE	 = YES
+FILE_PATTERNS    = *.c *.h
+EXAMPLE_PATH     = ../test
+IMAGE_PATH	 =
+QUIET            = YES
+
+EXTRACT_ALL	 = NO
+EXTRACT_STATIC	 = NO
+SHOW_INCLUDE_FILES = NO
+JAVADOC_AUTOBRIEF = NO
+INHERIT_DOCS	 = YES
+ENABLED_SECTIONS = ""
+MACRO_EXPANSION  = YES
+EXPAND_ONLY_PREDEF = YES
+PREDEFINED	 =
+
+OPTIMIZE_OUTPUT_FOR_C = YES
+TYPEDEF_HIDES_STRUCT = YES
+
+#INPUT_FILTER	 = inputfilter
+#FILTER_SOURCE_FILES = YES
+
+HTML_TIMESTAMP = NO