fix AttributeError eos_static_route (#32779)

Signed-off-by: Trishna Guha <trishnaguha17@gmail.com>

lib/ansible/modules/network/eos/eos_static_route.py

@@ -189,16 +189,17 @@ def main():
                            supports_check_mode=True)
 
     address = module.params['address']
+    if address is not None:
         prefix = address.split('/')[-1]
-    warnings = list()
-    check_args(module, warnings)
 
+    if address and prefix:
         if '/' not in address or not validate_ip_address(address.split('/')[0]):
             module.fail_json(msg='{} is not a valid IP address'.format(address))
 
         if not validate_prefix(prefix):
             module.fail_json(msg='Length of prefix should be between 0 and 32 bits')
 
+    warnings = list()
     result = {'changed': False}
     if warnings:
         result['warnings'] = warnings