Only generate VMOV.I64 instructions for loading constant floating point values...

Only generate VMOV.I64 instructions for loading constant floating point values if this instruction is supported by the currently selected fpu.

	PR target/2006764
	* config/tc-arm.c (move_or_literal_pool): Only generate a VMOV.I64
	instruction if supported by the currently selected fpu variant.
	* testsuite/gas/arm/vfpv3-ldr_immediate.s: Add test of this PR.
	* testsuite/gas/arm/vfpv3-ldr_immediate.d: Update expected disassembly.