DynamicTablesPkg: Remove duplicated words

In an effort to clean the documentation of the above
package, remove duplicated words.

Cc: Sami Mujawar <Sami.Mujawar@arm.com>
Cc: Alexei Fedorov <Alexei.Fedorov@arm.com>
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

DynamicTablesPkg/Library/Acpi/Arm/AcpiSsdtSerialPortLibArm/SsdtSerialPortGenerator.c

@@ -239,7 +239,7 @@ BuildSsdtSerialPortTableEx (
     return Status;
   }
 
-  // Setup the table list early so that that appropriate cleanup
+  // Setup the table list early so that appropriate cleanup
   // can be done in case of failure.
   *Table = TableList;