staging: rtl8712: add blank lines after declarations

Add blank lines after function/struct/union/enum declarations to adhere to
Linux kernel coding style.
Reported by checkpatch.

Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@gmail.com>
Link: https://lore.kernel.org/r/ffe2ab70ef3cb73d3d6dd19d88804af7ecb568a2.1617568354.git.zhansayabagdaulet@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>