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/pk.h b/include/mbedtls/pk.h
index ffd06dd..1e2a293 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -229,7 +229,7 @@
  *
  * \return          Key size in bits, or 0 on error
  */
-size_t mbedtls_pk_get_size( const mbedtls_pk_context *ctx );
+size_t mbedtls_pk_get_bitlen( const mbedtls_pk_context *ctx );
 
 /**
  * \brief           Get the length in bytes of the underlying key
@@ -239,7 +239,7 @@
  */
 static inline size_t mbedtls_pk_get_len( const mbedtls_pk_context *ctx )
 {
-    return( ( mbedtls_pk_get_size( ctx ) + 7 ) / 8 );
+    return( ( mbedtls_pk_get_bitlen( ctx ) + 7 ) / 8 );
 }
 
 /**