arm: omap3: Make secureworld_exit() static

secureworld_exit() is only used in one file, so make it static
to that file and remove it from sys_proto.h. This
may help with some further optimization in the future.

Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210625192308.277136-3-aford173@gmail.com
diff --git a/arch/arm/mach-omap2/omap3/board.c b/arch/arm/mach-omap2/omap3/board.c
index ef4fa80..41d0d3e 100644
--- a/arch/arm/mach-omap2/omap3/board.c
+++ b/arch/arm/mach-omap2/omap3/board.c
@@ -114,7 +114,7 @@
  *		configure secure registers and exit secure world
  *              general use.
  *****************************************************************************/
-void secureworld_exit(void)
+static void secureworld_exit(void)
 {
 	unsigned long i;