ASoC: Intel: Skylake: explicitly add the headers sst-dsp.h

Commit bdd0384a ("ASoC: Intel: Skylake: Add support to read firmware
registers") introduced firmware register read so added sst-dsp-priv.h but
missed adding sst-dsp.h as that leads to below compiler warning:

   In file included from sound/soc/intel/skylake/skl-debug.c:23:0:
>> sound/soc/intel/skylake/../common/sst-dsp-priv.h:63:42: warning:
'struct sst_pdata' declared inside parameter list [enabled by default]
     int (*init)(struct sst_dsp *sst, struct sst_pdata *pdata);
                                             ^
>> sound/soc/intel/skylake/../common/sst-dsp-priv.h:63:42: warning:
its scope is only this definition or declaration, which is probably
not what you want [enabled by default]

So add the missing header.

Fixes: bdd0384a ("ASoC: Intel: Skylake: Add support to read firmware registers")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Guneshwor Singh <guneshwor.o.singh@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/skylake/skl-debug.c

@@ -20,6 +20,7 @@
 #include "skl-sst-ipc.h"
 #include "skl-tplg-interface.h"
 #include "skl-topology.h"
+#include "../common/sst-dsp.h"
 #include "../common/sst-dsp-priv.h"
 
 #define MOD_BUF		PAGE_SIZE