cpu_map: Introduce ARM CPU features

The only feature we care about for the moment is SVE, which can
be controlled both with a coarse granularity by turning it on/off
completely and with a finer granularity by enabling/disabling
individual vector lengths.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Tested-by: NAndrew Jones <drjones@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

src/cpu_map/arm_features.xml

+<cpus>
+
+  <!-- SVE vector lengths -->
+  <feature name='sve'/>
+  <feature name='sve128'/>
+  <feature name='sve256'/>
+  <feature name='sve384'/>
+  <feature name='sve512'/>
+  <feature name='sve640'/>
+  <feature name='sve768'/>
+  <feature name='sve896'/>
+  <feature name='sve1024'/>
+  <feature name='sve1152'/>
+  <feature name='sve1280'/>
+  <feature name='sve1408'/>
+  <feature name='sve1536'/>
+  <feature name='sve1664'/>
+  <feature name='sve1792'/>
+  <feature name='sve1920'/>
+  <feature name='sve2048'/>
+
+</cpus>

src/cpu_map/index.xml

@@ -75,4 +75,8 @@
     <include filename="ppc64_POWERPC_e5500.xml"/>
     <include filename="ppc64_POWERPC_e6500.xml"/>
   </arch>
+
+  <arch name='arm'>
+    <include filename='arm_features.xml'/>
+  </arch>
 </cpus>