[APX PUSH2POP2] Adjust operand order for PUSH2POP2

[APX PUSH2POP2] Adjust operand order for PUSH2POP2

The push2/pop2 operand order does not match the binutils implementation
for AT&T syntax that it will first push operands[2] then operands[1].
Correct it by reverse operand order for AT&T syntax.

gcc/ChangeLog:

	* config/i386/i386.md (push2_di): Adjust operand order for AT&T
	syntax.
	(pop2_di): Likewise.
	(push2p_di): Likewise.
	(pop2p_di): Likewise.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/apx-push2pop2-1.c: Adjust output scan.
	* gcc.target/i386/apx-push2pop2_force_drap-1.c: Likewise.