Fix the name of cpu=aarch64

arm64 is the .deb architecture for it, not the bazel CPU name I see
used.

Change-Id: I46dbbc2478aae92b2a9dba0b8b11a8f54481ef9a
diff --git a/tools/BUILD b/tools/BUILD
index d77abf8..9bf2931 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -49,8 +49,8 @@
 )
 
 config_setting(
-    name = "cpu_arm64",
-    values = {"cpu": "arm64"},
+    name = "cpu_aarch64",
+    values = {"cpu": "aarch64"},
 )
 
 config_setting(
@@ -80,14 +80,14 @@
 
 environment(name = "cortex-m4f-k22")
 
-environment(name = "arm64")
+environment(name = "aarch64")
 
 environment_group(
     name = "cpus",
     defaults = [
         ":k8",
         ":roborio",
-        ":arm64",
+        ":aarch64",
         ":armhf-debian",
     ],
     environments = [
@@ -97,6 +97,6 @@
         ":armhf-debian",
         ":cortex-m4f",
         ":cortex-m4f-k22",
-        ":arm64",
+        ":aarch64",
     ],
 )