staging: rtl8712: style fix indentation

This patch fixes various coding style issues in the rtl8712 module as
noted by checkpatch.pl related to indentation.

It fixes the following checkpatch.pl warning:

WARNING: suspect code indent for conditional statements

Signed-off-by: Martin Homuth <martin@martinhomuth.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>