nds32: Add perf call-graph support.

The perf call-graph option can trace the callchain
between functions. This commit add the perf callchain
for nds32. There are kerenl callchain and user callchain.
The kerenl callchain can trace the function in kernel
space. There are two type for user callchain. One for the
'optimize for size' config is set, and another one for the
config is not set. The difference between two types is that
the index of frame-pointer in user stack is not the same.

For example:
	With optimize for size:
		User Stack:
			---------
			|   lp	|
			---------
			|	gp	|
			---------
			|	fp	|

	Without optimize for size:
		User Stack:
		1. non-leaf function:
			---------
			|	lp	|
			---------
			|	fp	|

		2. leaf	function:
			---------
			|	fp	|

Signed-off-by: Nickhu <nickhu@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>