x86/kprobes: Move 'inline' to the beginning of the kprobe_is_ss() declaration

Address this GCC warning:

  arch/x86/kernel/kprobes/core.c:940:1:
   warning: 'inline' is not at beginning of declaration [-Wold-style-declaration]
    940 | static int nokprobe_inline kprobe_is_ss(struct kprobe_ctlblk *kcb)
        | ^~~~~~

[ mingo: Tidied up the changelog. ]

Fixes: 6256e668

: ("x86/kprobes: Use int3 instead of debug trap for single-step")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20210324144502.1154883-1-weiyongjun1@huawei.com