testsuite: Fix typo when setting llvm_ways

Since 2014 llvm_ways has been set to [] so none of the tests which use
only_ways(llvm_ways) have worked as expected.

Hopefully the tests still pass with this typo fix!

testsuite/config/ghc

@@ -176,8 +176,7 @@ opt_ways      = [x[0] for x in config.way_flags.items()
                       if '-O' in x[1]]
 
 llvm_ways     = [x[0] for x in config.way_flags.items()
-                      if '-fflvm' in x[1]]
-
+                      if '-fllvm' in x[1]]
 
 def get_compiler_info():
     if config.unregisterised: