test: missing header

Signed-off-by: Slawomir Blauciak <slawomir.blauciak@linux.intel.com>

Author: slawblauciak

test/cmocka/src/lib/alloc/mock.c

@@ -30,6 +30,8 @@
 
 #include <stdint.h>
 
+#include <sof/alloc.h>
+
 struct dma_copy;
 struct dma_sg_config;