staging: rtl8188eu: Macros with complex values should be enclosed in parentheses

This macro is not used and also had a style error. I have run
grep and compiled the module to be sure.

Signed-off-by: Alfonso Lima Astor <alfonsolimaastor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>