staging: rtl8723bs: hal: rtl8723b_phycfg.c: Remove unnecessary parentheses

Challenge suggested by coccinelle.
Remove unnecessary parentheses around an expression.

Signed-off-by: Payal Kshirsagar <payal.s.kshirsagar.98@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>