ftrace: Move ARCH_SUPPORTS_FTRACE_SAVE_REGS in Kconfig

ftrace: Move ARCH_SUPPORTS_FTRACE_SAVE_REGS in Kconfig

Move SAVE_REGS support flag into Kconfig and rename
it to CONFIG_DYNAMIC_FTRACE_WITH_REGS. This also introduces
CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS which indicates
the architecture depending part of ftrace has a code
that saves full registers.
On the other hand, CONFIG_DYNAMIC_FTRACE_WITH_REGS indicates
the code is enabled.

Link: http://lkml.kernel.org/r/[email protected]
Cc: Ingo Molnar <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Signed-off-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>