Redo of PR#5345. Fixed spelling and typographical errors found by CodeSpell.

Signed-off-by: Shaun Case <warmsocks@gmail.com>
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index f700e3b..6d372b9 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -207,7 +207,7 @@
                     size_t len );
 
 /**
- * \brief               Initilisation of simpified HMAC_DRBG (never reseeds).
+ * \brief               Initialisation of simplified HMAC_DRBG (never reseeds).
  *
  * This function is meant for use in algorithms that need a pseudorandom
  * input such as deterministic ECDSA.