ARM: ftrace: enable function graph tracer

Add the options to enable the function graph tracer on ARM.  Function
graph tracer support requires frame pointers, so exclude Thumb-2 and
also make sure FRAME_POINTER gets enabled when FUNCTION_GRAPH_TRACER is
used, since FUNCTION_TRACER doesn't "select FRAME_POINTER" when
ARM_UNWIND is used.  Therefore, with GCC 4.4.0+, you get plain function
tracing without frame pointers, but you'll need them if you want
function graph tracing.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Rabin Vincent <rabin@rab.in>

arch/arm/Kconfig

@@ -14,6 +14,7 @@ config ARM
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
 	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
 	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)
+	select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
 	select HAVE_GENERIC_DMA_COHERENT
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZO

arch/arm/Kconfig.debug

@@ -23,7 +23,7 @@ config STRICT_DEVMEM
 config FRAME_POINTER
 	bool
 	depends on !THUMB2_KERNEL
-	default y if !ARM_UNWIND
+	default y if !ARM_UNWIND || FUNCTION_GRAPH_TRACER
 	help
 	  If you say N here, the resulting kernel will be slightly smaller and
 	  faster. However, if neither FRAME_POINTER nor ARM_UNWIND are enabled,