[arm] Specify +dotprod support for Cortex-A55 and Cortex-A75 in native system detection

Since support for -mcpu=cortex-a55 and -mcpu=cortex-a75
was added we added support for the +dotprod extension
which these CPUs support.

We already specify as such in the arm-cpus.in entries for
these processors. However the table in driver-arm.c was
not adding +dotproct to the -march string that it generates.

This patch fixes that oversight.
In the future I'd like to get the arm_cpu_table in driver-arm.c
be auto-generated somehow from the arm-cpus.in data so
that we don't have to keep track of discrepancies explicitly...

Bootstrapped and tested on arm-none-linux-gnueabihf.

	* config/arm/driver-arm.c (arm_cpu_table): Specify dotprod
	support for Cortex-A55 and Cortex-A75.

From-SVN: r255943

gcc/ChangeLog

 2017-12-21  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
+	* config/arm/driver-arm.c (arm_cpu_table): Specify dotprod
+	support for Cortex-A55 and Cortex-A75.
+
+2017-12-21  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
 	* common/config/arm/arm-common.c (compare_opt_names): Add function
 	comment.  Use strcmp instead of manual loop.
 

gcc/config/arm/driver-arm.c

@@ -54,8 +54,8 @@ static struct vendor_cpu arm_cpu_table[] = {
     {"0xd07", "armv8-a+crc", "cortex-a57"},
     {"0xd08", "armv8-a+crc", "cortex-a72"},
     {"0xd09", "armv8-a+crc", "cortex-a73"},
-    {"0xd05", "armv8.2-a+fp16", "cortex-a55"},
-    {"0xd0a", "armv8.2-a+fp16", "cortex-a75"},
+    {"0xd05", "armv8.2-a+fp16+dotprod", "cortex-a55"},
+    {"0xd0a", "armv8.2-a+fp16+dotprod", "cortex-a75"},
     {"0xc14", "armv7-r", "cortex-r4"},
     {"0xc15", "armv7-r", "cortex-r5"},
     {"0xc17", "armv7-r", "cortex-r7"},