i386: Refactor get_intel_cpu

From ISE, it shows that we will have family 0x13 for Diamond Rapids.
Therefore, we need to refactor the get_intel_cpu to accept new families.
Also I did some reorder in the switch for clearness by putting earlier
added products on top for search convenience.

gcc/ChangeLog:

	* common/config/i386/cpuinfo.h (get_intel_cpu): Refactor the
	function for future expansion on different family.