[harwdare] replace Unknonw par N/A for non-gpu ACC

lib/refrepo/gen/wiki/generators/hardware.rb

@@ -192,13 +192,13 @@ class G5KHardwareGenerator < WikiGenerator
                   vendor = acc['mic_vendor']
                   model = acc['mic_model']
                   compute_capability = { text: "N/A", sort: 0 }
-                  microarchitecture = 'Unknown'
+                  microarchitecture = 'N/A'
                   mem = RefRepo::Utils.get_as_gb(acc['mic_memory'])
                 when :FPGA
                   vendor = acc['vendor']
                   model = acc['model']
                   compute_capability = { text: "N/A", sort: 0 }
-                  microarchitecture = 'Unknown'
+                  microarchitecture = 'N/A'
                   mem = RefRepo::Utils.get_as_gb(acc['memory'])
                 end
 
@@ -367,7 +367,7 @@ class G5KHardwareGenerator < WikiGenerator
       'Pascal' => '2016',
       'Volta' => '2017',
       'Fermi' => '2010',
-      'Unknown' => '&nbsp;',
+      'N/A' => '&nbsp;',
     }
     date = release_dates[microarchitecture]
     raise "ERROR: microarchitecture not found: '#{microarchitecture}'. Add in hardware.rb" if date.nil?