staging/ft1000: fix the no brace needed warning in ft1000_interrupt

as the if statement encloses only one line braces around it are not
needed.

The following warn fixed,
WARNING: braces {} are not necessary for single statement blocks

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>