[AArch64] Replace insn to zero up SIMD registers

[AArch64] Replace insn to zero up SIMD registers

gcc/
	* config/aarch64/aarch64.md
	(*movhf_aarch64): Add "movi %0, #0" to zero up register and
	remove the "fp" attributes.
	(*movsf_aarch64): Add "movi %0, #0" to zero up register and
	add the "simd" attributes.
	(*movdf_aarch64): Likewise.
	(*movtf_aarch64): Remove the "fp" attributes.
	* testsuite/gcc.target/aarch64/fmovf-zero-reg.c: Update accordingly.
	* testsuite/gcc.target/aarch64/fmovd-zero-reg.c: Likewise.

From-SVN: r235532