core: Add dsp-core option for XTENSA compiler

In order to use native XTENSA compiler the core target needs to
be overwite with the good platform. This patch is adding an optional
option in order to be able to overwrite the core selection.

Example:
- Set Xtensa export PATH=$PATH:<PATH>/xtensa/XtDevTools/install/tools/RD-2012.5-linux/XtensaTools
./configure --with-arch=xtensa --with-platform=baytrail --with-dsp-core=CHT_audio_hifiep --with-root-dir=<PATH>/xtensa/XtDevTools/install/tools/RD-2012.5-linux/XtensaTools --host=xtensa CC=xt-xcc OBJCOPY=xt-objcopy OBJDUMP=xt-objdump
make
make bin

Signed-off-by: Sebastien Guiriec <sebastien.guiriec@intel.com>

configure.ac

@@ -113,6 +113,20 @@ case "$with_platform" in
     ;;
 esac
 
+# DSP core support (Optional)
+AC_ARG_WITH([dsp-core],
+        AS_HELP_STRING([--with-dsp-core], [Specify DSP Core]),
+	[], [with_dsp_core=no])
+
+case "$with_dsp_core" in
+    CHT_audio_hifiep*)
+	# BXT/CHT DSP Core
+	XTENSA_CORE="CHT_audio_hifiep"
+	AC_SUBST(XTENSA_CORE)
+    ;;
+
+esac
+
 # Test after CFLAGS set othewise test of cross compiler fails. 
 AM_PROG_AS
 AM_PROG_AR
@@ -157,6 +171,7 @@ echo "
 
 Target Architecture:           ${ARCH}
 Target Platform:               ${PLATFORM}
+Target Core:                   ${XTENSA_CORE}
 
 Compiler:                      ${CC}
 CFLAGS:                        ${CFLAGS}