gas: ARM: Fix encoding of VCVTr.s32.f64 instructions

gas: ARM: Fix encoding of VCVTr.s32.f64 instructions

The direct rounding floating-point VCVT instructions introduced in
ARMv8 encode the s32.f64 variant incorrectly. The op bit should be
set to 1 for all signed conversions.

gas/ChangeLog:

2014-01-17  Will Newton  <will.newton@linaro.org>

	* config/tc-arm.c (do_vfp_nsyn_cvt_fpv8): Set OP to 1
	for the s32.f64 flavours of VCVT.

gas/testsuite/ChangeLog:

2014-01-17  Will Newton  <will.newton@linaro.org>

	* gas/arm/armv8-a+fp.d: Correct encoding of vcvta.s32.f64.