[ARC] Fix move_double_src_operand predicate.

[ARC] Fix move_double_src_operand predicate.

Durring compilation process, (subreg (mem ...) ...) can occur. Hence,
we need to check if the address of mem is a valid one. This patch is
fixing this check by directly calling the address_operand, instead of
calling move_double_src_operand, as the latter is always checking
against the original mode, thus, returning false when the inner and
outer modes are different.

gcc/
2017-03-27  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/predicates.md (move_double_src_operand): Replace the
	call to move_double_src_operand with a call to address_operand.

From-SVN: r246499