aarch64: Add Demeter tuning structs

aarch64: Add Demeter tuning structs

This patch adds tuning structs for -mcpu/-mtune=demeter.

gcc/ChangeLog:

2022-03-22  Tamar Christina  <tamar.christina@arm.com>
	    Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* config/aarch64/aarch64.cc (demeter_addrcost_table,
	demeter_regmove_cost, demeter_advsimd_vector_cost,
	demeter_sve_vector_cost, demeter_scalar_issue_info,
	demeter_advsimd_issue_info, demeter_sve_issue_info,
	demeter_vec_issue_info, demeter_vector_cost,
	demeter_tunings): New tuning structs.
	(aarch64_ve_op_count::rename_cycles_per_iter): Enable for demeter
	tuning.
	* config/aarch64/aarch64-cores.def: Add entry for demeter.
	* config/aarch64/aarch64-tune.md (tune): Add demeter to list.