psa_crypto_rsa: remove unnecessary casting

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/psa_crypto_rsa.c b/library/psa_crypto_rsa.c
index 7da6012..cfa2da6 100644
--- a/library/psa_crypto_rsa.c
+++ b/library/psa_crypto_rsa.c
@@ -73,8 +73,8 @@
     if (PSA_KEY_TYPE_IS_KEY_PAIR(type)) {
         status = mbedtls_to_psa_error(mbedtls_rsa_key_parse(*p_rsa, data, data_length));
     } else {
-        unsigned char *p = (unsigned char *) data;
-        unsigned char *end = (unsigned char *) (data + data_length);
+        unsigned char *p = data;
+        unsigned char *end = (data + data_length);
         status = mbedtls_to_psa_error(mbedtls_rsa_pubkey_parse(*p_rsa, &p, end));
     }
     if (status != PSA_SUCCESS) {