staging: greybus: audio: delete unnecessary parentheses

Eliminate unneeded parentheses around the right hand side of an assignment.
Coccinelle semantic patch used:

@@
expression e1, e2;
identifier v;
@@

(
 v = (e1 == e2)
|
 v = (e1 != e2)
|
 v = (e1 <= e2)
|
 v = (e1 >= e2)
|
 v =
- (
	e1
- )
)

Signed-off-by: Eva Rachel Retuya <eraretuya@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>