[ARC] Fix FPX/FPUDA code gen when compiling for big-endian.

gcc/
2016-04-28  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.c (arc_process_double_reg_moves): Fix for
	big-endian compilation.
	(arc_rtx_costs): Fix high/low naming.
	* config/arc/arc.md (addf3): Likewise.
	(subdf3): Likewise.
	(muldf3): Likewise.

From-SVN: r235567