patch #8563: part #1 Add power reduction conditions to device headers

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2460 1084037a-409f-4a99-8160-1a4b3577d4c1
patch #8563: part #2 Removed device names to define power macros. Instead use power macro conditions from device header file.

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2461 1084037a-409f-4a99-8160-1a4b3577d4c1