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/include/mbedtls/pk.h b/include/mbedtls/pk.h
index ded5222..15d1a39 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -390,7 +390,7 @@
  */
 static inline size_t mbedtls_pk_get_len( const mbedtls_pk_context *ctx )
 {
-    return( ( mbedtls_pk_get_bitlen( ctx ) + 7 ) / 8 );
+    return ( mbedtls_pk_get_bitlen( ctx ) + 7 ) / 8 ;
 }
 
 /**