staging: fbtft: fix Macros with complex values should be enclosed in parentheses

This patch fixes the following checkpatch.pl error:
fix Macros with complex values should be enclosed in parentheses

Signed-off-by: Heba Aamer <heba93aamer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>