Tegra186: secondary: fix MISRA defects

Main fixes:

Added explicit casts (e.g. 0U) to integers in order for them to be
compatible with whatever operation they're used in [Rule 10.1]

Force operands of an operator to the same type category [Rule 10.4]

Voided non c-library functions whose return types are not used [Rule 17.7]

Change-Id: I758e7ef6d45dd2edf4cd5580e2af15219246e75c
Signed-off-by: Anthony Zhou <anzhou@nvidia.com>
diff --git a/plat/nvidia/tegra/include/tegra_private.h b/plat/nvidia/tegra/include/tegra_private.h
index ff3d6d2..d0028e0 100644
--- a/plat/nvidia/tegra/include/tegra_private.h
+++ b/plat/nvidia/tegra/include/tegra_private.h
@@ -66,7 +66,7 @@
 
 /* Declarations for plat_secondary.c */
 void plat_secondary_setup(void);
-int plat_lock_cpu_vectors(void);
+int32_t plat_lock_cpu_vectors(void);
 
 /* Declarations for tegra_fiq_glue.c */
 void tegra_fiq_handler_setup(void);