x86: Correct ISA enabled for clients since Arrow Lake

gcc/ChangeLog:

	* config/i386/i386.h: Correct the ISA enabled for Arrow Lake.
	Also make Clearwater Forest depends on Sierra Forest.
	* config/i386/i386-options.cc: Revise the order of the macro
	definition to avoid confusion.
	* doc/extend.texi: Revise documentation.
	* doc/invoke.texi: Correct documentation.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/funcspec-56.inc: Group Clearwater Forest
	with atom cores.