Fix parsing of rocminfo output for ISAs with no features defined

Patch is an internal port of
 https://github.com/RadeonOpenCompute/rocminfo/pull/59

Change-Id: Iea84f49a60abce73716a7451960c20ee0d2b7bca

rocm_agent_enumerator

@@ -92,7 +92,7 @@ def getGCNISA(line, match_from_beginning = False):
    return result.group(0)
  return None
 
-@staticVars(search_name=re.compile("gfx[0-9a-fA-F]+:[-+:\w]+"))
+@staticVars(search_name=re.compile("gfx[0-9a-fA-F]+(:[-+:\w]+)?"))
 def getGCNArchName(line):
  result = getGCNArchName.search_name.search(line)