fix(tree): correct some typos

found using codespell (https://github.com/codespell-project/codespell).

Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Change-Id: I1bfa797e3460adddeefa916bb68e22beddaf6373
diff --git a/plat/mediatek/include/mtk_sip_svc.h b/plat/mediatek/include/mtk_sip_svc.h
index f677915..684f951 100644
--- a/plat/mediatek/include/mtk_sip_svc.h
+++ b/plat/mediatek/include/mtk_sip_svc.h
@@ -97,7 +97,7 @@
 };
 
 /*
- * This function should be implemented in MediaTek SOC directory. It fullfills
+ * This function should be implemented in MediaTek SOC directory. It fulfills
  * MTK_SIP_SET_AUTHORIZED_SECURE_REG SiP call by checking the sreg with the
  * predefined secure register list, if a match was found, set val to sreg.
  *