codespell: Add ARCHTYPE to ignore list

ARCHTYPE is a valid abbreviation for 'architecture type' used
consistently across the codebase. This matches the nuttx repo's
.codespellrc configuration.

Signed-off-by: Huang Qi <huangqi3@xiaomi.com>

Author: no1wudi

.codespellrc

@@ -10,4 +10,4 @@ skip =
   LICENSE,
 
 # Ignore words list (FTP protocol commands and technical terms)
-ignore-words-list = ALLO
+ignore-words-list = ALLO, ARCHTYPE