include/arch/romstage: Fix typo

Change-Id: Ie0c80792210ded7f81184b60ba2b0b51c13db283
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38308
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/arch/x86/include/arch/romstage.h

@@ -75,7 +75,7 @@ void prepare_and_run_postcar(struct postcar_frame *pcf);
  * tears down CAR and loads ramstage. The postcar_frame object
  * indicates how to set up the frame. If caching is enabled at
  * the time of the call it is up to the platform code to handle
- * coherency with dirty lines in the cache using some mechansim
+ * coherency with dirty lines in the cache using some mechanism
  * such as platform_prog_run() because run_postcar_phase()
  * utilizes prog_run() internally.
  */