[autotest] site_linux_system: eliminate redundant if/else

The 'else' is essentially equivalent to the 'if'.

BUG=none
TEST=wifi_matfunc

Change-Id: Ia78a0bd060252101bbc2038acf3457585e531a28
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1162985
Commit-Ready: Kirtika Ruchandani <kirtika@chromium.org>
Tested-by: Kirtika Ruchandani <kirtika@chromium.org>
Reviewed-by: Kirtika Ruchandani <kirtika@chromium.org>
diff --git a/server/site_linux_router.py b/server/site_linux_router.py
index 96c4ee7..37fa42e 100644
--- a/server/site_linux_router.py
+++ b/server/site_linux_router.py
@@ -272,11 +272,8 @@
 
         """
         # Figure out the correct interface.
-        if configuration.min_streams is None:
-            interface = self.get_wlanif(configuration.frequency, 'managed')
-        else:
-            interface = self.get_wlanif(
-                configuration.frequency, 'managed', configuration.min_streams)
+        interface = self.get_wlanif(configuration.frequency, 'managed',
+                                    configuration.min_streams)
         phy_name = self.iw_runner.get_interface(interface).phy
 
         conf_file = self.HOSTAPD_CONF_FILE_PATTERN % interface