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/library/x509_crt.c b/library/x509_crt.c
index bedc6e9..7cb5b44 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -180,7 +180,7 @@
 #if defined(MBEDTLS_RSA_C)
     if( pk_alg == MBEDTLS_PK_RSA || pk_alg == MBEDTLS_PK_RSASSA_PSS )
     {
-        if( mbedtls_pk_get_size( pk ) >= profile->rsa_min_bitlen )
+        if( mbedtls_pk_get_bitlen( pk ) >= profile->rsa_min_bitlen )
             return( 0 );
 
         return( -1 );
@@ -1438,7 +1438,7 @@
     }
 
     ret = mbedtls_snprintf( p, n, "\n%s%-" BC "s: %d bits", prefix, key_size_str,
-                          (int) mbedtls_pk_get_size( &crt->pk ) );
+                          (int) mbedtls_pk_get_bitlen( &crt->pk ) );
     SAFE_SNPRINTF();
 
     /*