accel/qaic: initialize ret variable to 0

clang static analysis reports
drivers/accel/qaic/qaic_data.c:610:2: warning: Undefined or garbage
  value returned to caller [core.uninitialized.UndefReturn]
        return ret;
        ^~~~~~~~~~

From a code analysis of the function, the ret variable is only set some
of the time but is always returned.  This suggests ret can return
uninitialized garbage. However BO allocation will ensure ret is always
set in reality.

Initialize ret to 0 to silence the warning.

Fixes: ff13be83 ("accel/qaic: Add datapath")
Signed-off-by: Tom Rix <trix@redhat.com>
[jhugo: Reword commit text]
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Carl Vanderlip <quic_carlv@quicinc.com>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230517165605.16770-1-quic_jhugo@quicinc.com

drivers/accel/qaic/qaic_data.c

@@ -591,7 +591,7 @@ static int qaic_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struc
 	struct qaic_bo *bo = to_qaic_bo(obj);
 	unsigned long offset = 0;
 	struct scatterlist *sg;
-	int ret;
+	int ret = 0;
 
 	if (obj->import_attach)
 		return -EINVAL;