cpu/intel/stm: Use official spelling of *Kaby Lake*

Change-Id: I8e049931e48eebcf66773bce3126532f0a405b38
Signed-off-by: Paul Menzel <[email protected]>

Author: paulmenzel

cpu/intel/stm/README.md

@@ -11,7 +11,7 @@ Dec 3, 2019
 ## Supported silicon:
 
 The STM is designed to be BIOS, platform, and operating system agnostic.
-It has been tested on the Purism Librem 15v4 (Kabylake), Dell 990
+It has been tested on the Purism Librem 15v4 (Kaby Lake), Dell 990
 (Sandybridge with a non-coreboot BIOS), and Minnowboard Max (Atom).
 
 ## Instructions: