[Arm] Set Armv7-A tune to Cortex-A53

By default Armv7-A tunes for Cortex-A8. This is an ancient core
today and the settings are no longer useful for newer cores. So
switch to Cortex-A53 tuning since it works well across a wide range
of modern cores.

On SPECINT2006 the performance gain is 0.7% compared to Cortex-A8 tuning,
and codesize reduces by 0.2%.

    gcc/
	* config/arm/arm-cpus.in (armv7): Set tune to Cortex-A53.
	(armv7-a): Likewise.
	(armv7ve): Likewise.

From-SVN: r278447

gcc/ChangeLog

+2019-11-19  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* config/arm/arm-cpus.in (armv7): Set tune to Cortex-A53.
+	(armv7-a): Likewise.
+	(armv7ve): Likewise.
+
 2019-11-19  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/92581

gcc/config/arm/arm-cpus.in

@@ -415,7 +415,7 @@ begin arch armv6s-m
 end arch armv6s-m
 
 begin arch armv7
- tune for cortex-a8
+ tune for cortex-a53
  tune flags CO_PROC
  base 7
  isa ARMv7
@@ -426,7 +426,7 @@ begin arch armv7
 end arch armv7
 
 begin arch armv7-a
- tune for cortex-a8
+ tune for cortex-a53
  tune flags CO_PROC
  base 7A
  profile A
@@ -451,7 +451,7 @@ begin arch armv7-a
 end arch armv7-a
 
 begin arch armv7ve
- tune for cortex-a8
+ tune for cortex-a53
  tune flags CO_PROC
  base 7A
  profile A