arm64: function_graph: Remove use of FTRACE_NOTRACE_DEPTH

Functions in the set_graph_notrace no longer subtract FTRACE_NOTRACE_DEPTH
from curr_ret_stack, as that is now implemented via the trace_recursion
flags. Access to curr_ret_stack no longer needs to worry about checking for
this. curr_ret_stack is still initialized to -1, when there's not a shadow
stack allocated.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

arch/arm64/kernel/stacktrace.c

@@ -61,9 +61,6 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 			(frame->pc == (unsigned long)return_to_handler)) {
 		if (WARN_ON_ONCE(frame->graph == -1))
 			return -EINVAL;
-		if (frame->graph < -1)
-			frame->graph += FTRACE_NOTRACE_DEPTH;
-
 		/*
 		 * This is a case where function graph tracer has
 		 * modified a return address (LR) in a stack frame