Fix parantheses on return and sizeof statements.

Used script:
```
import re
import sys

for arg in sys.argv[1:]:
    print(arg)
    with open(arg, 'r') as file:
        content = file.read()
        content = re.sub(r"return\s?\((?!.*\).*\()\s*\n?(.*)\n?\);", r"return \1;", \
            content, flags = re.M)
        content = re.sub(r"sizeof ([^\(][a-zA-Z0-9_\[\]]*)", r"sizeof(\1)",\
            content, flags = re.M)
    with open(arg, 'w') as file:
        file.write(content)

```
Executed with:
` find . -regextype posix-egrep -regex ".*\.([hc]|fmt|function)" | xargs -L1 python script.py`

Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
diff --git a/library/threading.c b/library/threading.c
index bae6644..cf01c0a 100644
--- a/library/threading.c
+++ b/library/threading.c
@@ -88,23 +88,23 @@
 static int threading_mutex_lock_pthread( mbedtls_threading_mutex_t *mutex )
 {
     if( mutex == NULL || ! mutex->is_valid )
-        return( MBEDTLS_ERR_THREADING_BAD_INPUT_DATA );
+        return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA ;
 
     if( pthread_mutex_lock( &mutex->mutex ) != 0 )
-        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
+        return MBEDTLS_ERR_THREADING_MUTEX_ERROR ;
 
-    return( 0 );
+    return 0 ;
 }
 
 static int threading_mutex_unlock_pthread( mbedtls_threading_mutex_t *mutex )
 {
     if( mutex == NULL || ! mutex->is_valid )
-        return( MBEDTLS_ERR_THREADING_BAD_INPUT_DATA );
+        return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA ;
 
     if( pthread_mutex_unlock( &mutex->mutex ) != 0 )
-        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
+        return MBEDTLS_ERR_THREADING_MUTEX_ERROR ;
 
-    return( 0 );
+    return 0 ;
 }
 
 void (*mbedtls_mutex_init)( mbedtls_threading_mutex_t * ) = threading_mutex_init_pthread;
@@ -123,7 +123,7 @@
 static int threading_mutex_fail( mbedtls_threading_mutex_t *mutex )
 {
     ((void) mutex );
-    return( MBEDTLS_ERR_THREADING_BAD_INPUT_DATA );
+    return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA ;
 }
 static void threading_mutex_dummy( mbedtls_threading_mutex_t *mutex )
 {