brcmsmac: Remove unnecessary parentheses

This patch fixes the clang warning of extraneous parentheses, with the
following coccinelle script.

@@
identifier i;
expression e;
statement s;
@@
if (
-(i == e)
+i == e
 )
s

Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Varsha Rao <rvarsha016@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>