signal/arm64: In ptrace_hbptriggered name the signal description string

This will let the description be reused shortly.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

arch/arm64/kernel/ptrace.c

@@ -182,6 +182,7 @@ static void ptrace_hbptriggered(struct perf_event *bp,
 				struct pt_regs *regs)
 {
 	struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
+	const char *desc = "Hardware breakpoint trap (ptrace)";
 
 #ifdef CONFIG_COMPAT
 	if (is_compat_task()) {
@@ -206,7 +207,7 @@ static void ptrace_hbptriggered(struct perf_event *bp,
 #endif
 	arm64_force_sig_fault(SIGTRAP, TRAP_HWBKPT,
 			      (void __user *)(bkpt->trigger),
-			      "Hardware breakpoint trap (ptrace)");
+			      desc);
 }
 
 /*