[arm] Eliminate TARGET_FPU_NAME

[arm] Eliminate TARGET_FPU_NAME

Rather than assuming a specific fpu name has been selected, we work
out the FPU from the ISA properties.  This is necessary since once we
have default FPUs selected by the processor, there will be no explicit
entry in the table of fpus to refer to.

This also fixes a bug with the code I added recently to permit new
aliases for existing FPU names: the new names cannot be passed to the
assembler since it does not recognize them.  By mapping the ISA
features back to the canonical names we avoid having to teach the
assembler about the new names.

	* arm.h (TARGET_FPU_NAME): Delete.
	* arm.c (arm_identify_fpu_from_isa): New function.
	(arm_declare_function_name): Use it to get the name for the FPU.

From-SVN: r243711