gpu: nvgpu: fix build errors on qnx for therm

- include therm header file in source file
- remove unreferenced function

JIRA VQRM-2343

Change-Id: Ibfeaf1e431631fa2b9a8e8f1bf044c17edc018c5
Signed-off-by: Richard Zhao <rizhao@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1706201
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: Sourab Gupta <sourabg@nvidia.com>
Tested-by: Sourab Gupta <sourabg@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Nirav Patel <nipatel@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/gv11b/therm_gv11b.c

@@ -23,6 +23,7 @@
  */
 
 #include "gk20a/gk20a.h"
+#include "therm_gv11b.h"
 
 #include <nvgpu/soc.h>