staging: xgifb: Remove unnecessary parentheses.

The removed parentheses are unnecessary and don't add readability.

Found using Coccinelle semantic patch:
@@ expression e, e1, e2; @@
e &=
(
        (e1 == e2)
|
-       (e1)
+       e1
)

@@ expression e, e1, e2; @@
e |=
(
        (e1 == e2)
|
-       (e1)
+       e1
)

Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>