[NDS32] Rename some variables so that we can clearly identify they represent general...

[NDS32] Rename some variables so that we can clearly identify they represent general purpose registers.

gcc/
	* config/nds32/nds32.h (callee_saved_regs_size): Rename to ...
	(callee_saved_gpr_regs_size): ... this.
	(callee_saved_regs_first_regno): Rename to ...
	(callee_saved_first_gpr_regno): ... this.
	(callee_saved_regs_last_regno) Rename to ...
	(callee_saved_last_gpr_regno): ... this.
	* config/nds32/nds32.c (nds32_compute_stack_frame): Adjust renamed
	variables.
	(nds32_initial_elimination_offset): Likewise.
	(nds32_expand_prologue): Likewise.
	(nds32_expand_epilogue): Likewise.
	(nds32_expand_prologue_v3push): Likewise.
	(nds32_expand_epilogue_v3pop): Likewise.
	* config/nds32/nds32-md-auxiliary.c (nds32_output_stack_push):
	Adjust renamed variables.
	(nds32_output_stack_pop): Likewise.

From-SVN: r221306