staging: greybus: sdio.c: Remove unncessary paranthesis.

Challenge suggested by coccinelle.
Remove unnecessary parathesis around the right hand of
assignment using the below script.

@@
binary operator op = {==,!=,&&,||,>=,<=,&,|};
expression l, r, t;
@@

(
l = (r op t)
|
l =
-(
r
-)
)

Signed-off-by: Sanjana Sanikommu <sanjana99reddy99@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>