Rename relevant global symbols from size to bitlen

Just applying rename.pl with this file:

mbedtls_cipher_get_key_size mbedtls_cipher_get_key_bitlen
mbedtls_pk_get_size mbedtls_pk_get_bitlen
MBEDTLS_BLOWFISH_MIN_KEY MBEDTLS_BLOWFISH_MIN_KEY_BITS
MBEDTLS_BLOWFISH_MAX_KEY MBEDTLS_BLOWFISH_MAX_KEY_BITS
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 9f42f0e..6710a00 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -415,7 +415,7 @@
  *                      MBEDTLS_KEY_LENGTH_NONE if ctx has not been
  *                      initialised.
  */
-static inline int mbedtls_cipher_get_key_size( const mbedtls_cipher_context_t *ctx )
+static inline int mbedtls_cipher_get_key_bitlen( const mbedtls_cipher_context_t *ctx )
 {
     if( NULL == ctx || NULL == ctx->cipher_info )
         return MBEDTLS_KEY_LENGTH_NONE;