ftrace: Hide one more entry in stack trace when ftrace_pid is enabled

ftrace: Hide one more entry in stack trace when ftrace_pid is enabled

On setting set_ftrace_pid, a extra entry generated by ftrace_pid_func()
is shown on stack trace(CONFIG_UNWINDER_FRAME_POINTER=y).

        [004] .....    68.459382: <stack trace>
 => 0xffffffffa00090af
 => ksys_read
 => __x64_sys_read
 => x64_sys_call
 => do_syscall_64
 => entry_SYSCALL_64_after_hwframe

To resolve this issue, increment skip count
in function_stack_trace_call() if pids are set.

Link: https://lore.kernel.org/linux-trace-kernel/20240528032604.6813-3-tatsuya.s2862@gmail.com
Signed-off-by: Tatsuya S <tatsuya.s2862@gmail.com>
[ Rebased to current tree ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>