hal: initialize variables

Initialize variables to prevent uninitialized use.

CRs-Fixed: 2125795
Change-Id: Idd1c1a1f20b360e5f73e41f36bcf91faf40520af
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 4af9a1b..eba36ff 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -4609,8 +4609,8 @@
     struct stream_out *out = (struct stream_out *)stream;
     struct audio_device *adev = out->dev;
     int ret = 0;
-    unsigned int offset1;
-    unsigned int frames1;
+    unsigned int offset1 = 0;
+    unsigned int frames1 = 0;
     const char *step = "";
     uint32_t mmap_size;