Fix up wlan_mac.bin to make the driver happy

- Remove : from the MACs in the file: kernel driver does not understand
these
- Remove all but one addresses, so we only set a MAC for wlan0.
Duplicate MACs aren't allowed, and we only have one available for this
purpose.

Change-Id: Ibf0b53c4f360c355eef501af0832889a49be2985
diff --git a/etc/runonce.d/10-set-mac-addresses b/etc/runonce.d/10-set-mac-addresses
index a5dbbe8..893ebd4 100755
--- a/etc/runonce.d/10-set-mac-addresses
+++ b/etc/runonce.d/10-set-mac-addresses
@@ -29,9 +29,6 @@
 
 WIFI_CONFIG_TEMPLATE = '''\
 Intf0MacAddress={0}
-Intf1MacAddress={0}
-Intf2MacAddress={0}
-Intf3MacAddress={0}
 END
 '''
 
@@ -116,7 +113,7 @@
     '''Writes the given MAC address string to the wifi configuration files.'''
     try:
         with open(WIFI_ADDR_PATH, 'w') as fp:
-            fp.write(WIFI_CONFIG_TEMPLATE.format(next_mac))
+            fp.write(WIFI_CONFIG_TEMPLATE.format(next_mac.translate(None, ':')))
         return True
     except Exception as e:
         print('Error writing wifi configuration to %s: %s' % (WIFI_ADDR_PATH, e))