Remove duplicate conditional statement

It contains two same conditional statements to check whether the first
argurment is end with '.ring.gz'. The latter one can be covered by 'else'
clause.

Change-Id: I4b67dc330e82e793020bec4b74047062313ae11c
Signed-off-by: Lin Yang <lin.a.yang@intel.com>

swift/common/ring/utils.py

@@ -280,7 +280,6 @@ def parse_builder_ring_filename_args(argvish):
             ring_file = first_arg
         else:
             ring_file = builder_file[:-len('.builder')]
-    if not first_arg.endswith('.ring.gz'):
         ring_file += '.ring.gz'
     return builder_file, ring_file