rtlwifi: Remove unnecessary parentheses

This is merged by Ping-Ke Shih from commit a221cb09 ("staging:
rtlwifi: Remove unnecessary parentheses"), and original commit log
is reserved below.

Remove unnecessary parentheses to comply with preferred coding style for
the linux kernel and avoid the following checkpatch's message:
'CHECK: Unnecessary parentheses around'.

Credits to checkpatch.

Signed-off-by: Frank A. Cancio Bello <frank@generalsoftwareinc.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>