openrisc/traps: Declare file scope symbols as static

Sparse was reporting the following warnings:

    arch/openrisc/kernel/traps.c:37:5: warning: symbol 'kstack_depth_to_print' was not declared. Should it be static?
    arch/openrisc/kernel/traps.c:39:22: warning: symbol 'lwa_addr' was not declared. Should it be static?
    arch/openrisc/kernel/traps.c:41:6: warning: symbol 'print_trace' was not declared. Should it be static?

The function print_trace and local variables kstack_depth_to_print and
lwa_addr are not used outside of this file.  This patch marks them as
static.
Signed-off-by: Stafford Horne <shorne@gmail.com>

arch/openrisc/kernel/traps.c

@@ -34,11 +34,11 @@
 #include <asm/unwinder.h>
 #include <asm/sections.h>
 
-int kstack_depth_to_print = 0x180;
+static int kstack_depth_to_print = 0x180;
 int lwa_flag;
-unsigned long __user *lwa_addr;
+static unsigned long __user *lwa_addr;
 
-void print_trace(void *data, unsigned long addr, int reliable)
+static void print_trace(void *data, unsigned long addr, int reliable)
 {
 	const char *loglvl = data;