Fix multiple quality issues in the source

This PR fixes multiple issues in the source code to address issues raised by
tests/scripts/check-files.py. Specifically:
 * incorrect file permissions
 * missing newline at the end of files
 * trailing whitespace
 * Tabs present
 * TODOs in the souce code
diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h
index 8e34e62..9dd4e67 100644
--- a/include/mbedtls/rsa.h
+++ b/include/mbedtls/rsa.h
@@ -345,7 +345,7 @@
  *                 as large as the size ctx->len of ctx->N (eg. 128 bytes
  *                 if RSA-1024 is used) to be able to hold an arbitrary
  *                 decrypted message. If it is not large enough to hold
- *                 the decryption of the particular ciphertext provided, 
+ *                 the decryption of the particular ciphertext provided,
  *                 the function will return MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
  *
  * \note           The input buffer must be as large as the size
@@ -377,7 +377,7 @@
  *                 as large as the size ctx->len of ctx->N (eg. 128 bytes
  *                 if RSA-1024 is used) to be able to hold an arbitrary
  *                 decrypted message. If it is not large enough to hold
- *                 the decryption of the particular ciphertext provided, 
+ *                 the decryption of the particular ciphertext provided,
  *                 the function will return MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
  *
  * \note           The input buffer must be as large as the size
@@ -411,10 +411,10 @@
  *                 as large as the size ctx->len of ctx->N (eg. 128 bytes
  *                 if RSA-1024 is used) to be able to hold an arbitrary
  *                 decrypted message. If it is not large enough to hold
- *                 the decryption of the particular ciphertext provided, 
+ *                 the decryption of the particular ciphertext provided,
  *                 the function will return MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE.
  *
- * \note           The input buffer must be as large as the size 
+ * \note           The input buffer must be as large as the size
  *                 of ctx->N (eg. 128 bytes if RSA-1024 is used).
  */
 int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,