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/tests/src/helpers.c b/tests/src/helpers.c
index 4d3d53d..7bbfa50 100644
--- a/tests/src/helpers.c
+++ b/tests/src/helpers.c
@@ -37,7 +37,7 @@
 #if defined(MBEDTLS_PLATFORM_C)
     ret = mbedtls_platform_setup( &platform_ctx );
 #endif /* MBEDTLS_PLATFORM_C */
-    return( ret );
+    return ret ;
 }
 
 void mbedtls_test_platform_teardown( void )
@@ -56,9 +56,9 @@
     else if( ( c >= 'A' ) && ( c <= 'F' ) )
         *uc = c - 'A' + 10;
     else
-        return( -1 );
+        return -1 ;
 
-    return( 0 );
+    return 0 ;
 }
 
 void mbedtls_test_fail( const char *test, int line_no, const char* filename )
@@ -108,24 +108,24 @@
 
     /* Must be even number of bytes. */
     if ( ( *len ) & 1 )
-        return( -1 );
+        return -1 ;
     *len /= 2;
 
     if ( (*len) > obufmax )
-        return( -1 );
+        return -1 ;
 
     while( *ibuf != 0 )
     {
         if ( ascii2uc( *(ibuf++), &uc ) != 0 )
-            return( -1 );
+            return -1 ;
 
         if ( ascii2uc( *(ibuf++), &uc2 ) != 0 )
-            return( -1 );
+            return -1 ;
 
         *(obuf++) = ( uc << 4 ) | uc2;
     }
 
-    return( 0 );
+    return 0 ;
 }
 
 void mbedtls_test_hexify( unsigned char *obuf,
@@ -164,7 +164,7 @@
 
     memset( p, 0x00, actual_len );
 
-    return( p );
+    return p ;
 }
 
 unsigned char *mbedtls_test_unhexify_alloc( const char *ibuf, size_t *olen )
@@ -175,13 +175,13 @@
     *olen = strlen( ibuf ) / 2;
 
     if( *olen == 0 )
-        return( mbedtls_test_zero_alloc( *olen ) );
+        return mbedtls_test_zero_alloc( *olen ) ;
 
     obuf = mbedtls_calloc( 1, *olen );
     TEST_HELPER_ASSERT( obuf != NULL );
     TEST_HELPER_ASSERT( mbedtls_test_unhexify( obuf, *olen, ibuf, &len ) == 0 );
 
-    return( obuf );
+    return obuf ;
 }
 
 int mbedtls_test_hexcmp( uint8_t * a, uint8_t * b,
@@ -191,7 +191,7 @@
     uint32_t i = 0;
 
     if( a_len != b_len )
-        return( -1 );
+        return -1 ;
 
     for( i = 0; i < a_len; i++ )
     {
@@ -268,9 +268,9 @@
     if( s[0] == 0 )
     {
         mbedtls_mpi_free( X );
-        return( 0 );
+        return 0 ;
     }
     else
-        return( mbedtls_mpi_read_string( X, radix, s ) );
+        return mbedtls_mpi_read_string( X, radix, s ) ;
 }
 #endif