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/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index 1372668..5c184cb 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -12,10 +12,10 @@
 static int sign_is_valid( const mbedtls_mpi *X )
 {
     if( X->s != 1 && X->s != -1 )
-        return( 0 ); // invalid sign bit, e.g. 0
+        return 0 ; // invalid sign bit, e.g. 0
     if( mbedtls_mpi_bitlen( X ) == 0 && X->s != 1 )
-        return( 0 ); // negative zero
-    return( 1 );
+        return 0 ; // negative zero
+    return 1 ;
 }
 
 typedef struct mbedtls_test_mpi_random
@@ -38,12 +38,12 @@
     mbedtls_test_mpi_random *random = (mbedtls_test_mpi_random*) state;
 
     if( random == NULL || random->data->x == NULL || buf == NULL )
-        return( -1 );
+        return -1 ;
 
     if( random->pos + random->chunk_len > random->data->len
             || random->chunk_len > len )
     {
-        return( -1 );
+        return -1 ;
     }
 
     memset( buf, 0, len );
@@ -58,7 +58,7 @@
 
     random->pos += random->chunk_len;
 
-    return( 0 );
+    return 0 ;
 }
 
 /* Random generator that is told how many bytes to return. */
@@ -69,11 +69,11 @@
     for( i = 0; i < len; i++ )
     {
         if( *bytes_left == 0 )
-            return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
+            return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ;
         buf[i] = *bytes_left & 0xff;
         --( *bytes_left );
     }
-    return( 0 );
+    return 0 ;
 }
 
 /* Test whether bytes represents (in big-endian base 256) a number b that
@@ -101,7 +101,7 @@
     }
     /* 0 is not significantly above a power of 2 */
     if( len == 0 )
-        return( 0 );
+        return 0 ;
     /* Extract the (up to) 2 most significant bytes */
     if( len == 1 )
         x = p[0];
@@ -117,7 +117,7 @@
      * a power of 2 iff x is significantly above 0 compared to 2^8.
      * Testing x >= 2^4 amounts to picking A = 1/16 in the function
      * description above. */
-    return( x >= 0x10 );
+    return x >= 0x10 ;
 }
 
 /* END_HEADER */