[AArch64] Change iterator for neg<mode>2 from VDQM to VDQ.

gcc/
	* config/aarch64/aarch64-simd.md (neg<mode>2): Use VDQ iterator.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@198306 138bc75d-0d04-0410-961f-82ee72b054a4