csky: Fixup compile error for abiv1 entry.S

This bug is from uprobe signal definition in thread_info.h. The
instruction (andi) of abiv1 immediate is smaller than abiv2, then
it will cause:

  AS      arch/csky/kernel/entry.o
 arch/csky/kernel/entry.S: Assembler messages:
 arch/csky/kernel/entry.S:224: Error: Operand 2 immediate is overflow.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>