wil6210: coding style fixes

- parentheses, indentation, typos
- seq_puts() instead of seq_printf() with single argument
- sizeof(var) vs. sizeof(type)

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>