net: tsec: fsl_mdio: Fix several cosmetic issues

Clean up the tsec and fsl_mdio driver codes a little bit, by:
- Fix misuse of tab and space here and there
- Use correct multi-line comment format
- Replace license identifier to GPL-2.0+

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>