Fix this warning by removing a unneeded use of defined

TIMEC   kernel/timeconst.h
defined(@array) is deprecated at kernel/timeconst.pl line 373.
  (Maybe you should just omit the defined()?)
http://linux-kernel.2935.n7.nabble.com/PATCH-1-5-kbuild-remove-deprecated-use-of-defined-in-timeconst-pl-td556009.html