csky: fix csky_cmpxchg_fixup not working

In the csky_cmpxchg_fixup function, it is incorrect to use the global
variable csky_cmpxchg_stw to determine the address where the exception
occurred.The global variable csky_cmpxchg_stw stores the opcode at the
time of the exception, while &csky_cmpxchg_stw shows the address where
the exception occurred.

Signed-off-by: Yang Li <[e-mail]>
Signed-off-by: Guo Ren <[e-mail]>

arch/csky/mm/fault.c

···
 	if (trap_no(regs) != VEC_TLBMODIFIED)
 		return;
 
-	if (instruction_pointer(regs) == csky_cmpxchg_stw)
-		instruction_pointer_set(regs, csky_cmpxchg_ldw);
+	if (instruction_pointer(regs) == (unsigned long)&csky_cmpxchg_stw)
+		instruction_pointer_set(regs, (unsigned long)&csky_cmpxchg_ldw);
 	return;
 }
 #endif