csky: Fixup compile error

From: Guo Ren <[email protected]>

Add header file for asmlinkage macro.

Error log:
In file included from arch/csky/include/asm/ptrace.h:7,
from arch/csky/include/asm/elf.h:6,
from include/linux/elf.h:6,
from kernel/extable.c:6:
arch/csky/include/asm/traps.h:43:11: error: expected ';' before 'void'

   43 | asmlinkage void do_trap_unknown(struct pt_regs *regs);
      |           ^~~~~

---
 arch/csky/include/asm/traps.h | 2 ++
 1 file changed, 2 insertions(+)

index 1e7d303b91e9..732c4aaa2e26 100644
@@ -3,6 +3,8 @@
 #ifndef __ASM_CSKY_TRAPS_H
 #define __ASM_CSKY_TRAPS_H
 
+#include <linux/linkage.h>
+
 #define VEC_RESET	0
 #define VEC_ALIGN	1
 #define VEC_ACCESS	2

2.36.1