FIH: Protect tfm_hal_boundary_need_switch()

This function is called to decide whether to change the hardware
protection when switching between partitions. As such, it is vital
that it is actually called, so use FIH_CALL()/FIH_RET().

Signed-off-by: Chris Brand <chris.brand@cypress.com>
Change-Id: I9f77378f4499d8a86102aec5e813185d3987c3c7
diff --git a/platform/include/tfm_hal_isolation.h b/platform/include/tfm_hal_isolation.h
index 238a8fd..2ae0abb 100644
--- a/platform/include/tfm_hal_isolation.h
+++ b/platform/include/tfm_hal_isolation.h
@@ -122,8 +122,8 @@
  * \return true  - a switching is needed.
  *         false - do not need a switch.
  */
-bool tfm_hal_boundary_need_switch(uintptr_t boundary_from,
-                                  uintptr_t boundary_to);
+FIH_RET_TYPE(bool) tfm_hal_boundary_need_switch(uintptr_t boundary_from,
+                                                uintptr_t boundary_to);
 
 #ifdef __cplusplus
 }