[ARM] Make issue rate part of per-core tuning structs

[ARM] Make issue rate part of per-core tuning structs

	* config/arm/arm-protos.h (struct tune_params): Add issue_rate field.
	* config/arm/arm.c (arm_slowmul_tune, arm_fastmul_tune,
	arm_strongarm_tune, arm_xscale_tune, arm_9e_tune, arm_v6t2_tune,
	arm_cortex_tune, arm_cortex_a8_tune, arm_cortex_a7_tune,
	arm_cortex_a15_tune, arm_cortex_a53_tune, arm_cortex_a57_tune,
	arm_cortex_a9_tune, arm_cortex_a12_tune, arm_v7m_tune, arm_v6m_tune,
	arm_fa726te_tune arm_cortex_a5_tune, arm_xgene1_tune):
	Specify issue_rate value.
	(arm_issue_rate): Look up issue rate from tuning structs. Remove
	large switch statement.
	(arm_marvell_pj4_tune): New struct.
	* config/arm/arm-cores.def (marvell-pj4): Use arm_marvell_pj4_tune
	struct.

From-SVN: r222356