src/mainboard to src/security: Fix spelling errors

These issues were found and fixed by codespell, a useful tool for
finding spelling errors.

Signed-off-by: Martin Roth <martin@coreboot.org>
Change-Id: Ie34003a9fdfe9f3b1b8ec0789aeca8b9435c9c79
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58081
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/security/intel/txt/common.c b/src/security/intel/txt/common.c
index 2b7d926..e3e2f5c 100644
--- a/src/security/intel/txt/common.c
+++ b/src/security/intel/txt/common.c
@@ -150,7 +150,7 @@
 }
 
 /**
- * Validate that the provided ACM is useable on this platform.
+ * Validate that the provided ACM is usable on this platform.
  */
 static int validate_acm(const void *ptr)
 {