net: hdlc_fr: add some required spaces

Add spaces required after that close brace '}'.
Add spaces required before the open parenthesis '('.
Add spaces required after that ','.
Add spaces required around that '='.

Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>