ManhattanStyle: Fix wrong operator precedence

!option->state & State_Enabled is accidentially satisfied because
State_Enabled is 1, so the condition is true for any non-zero value of
option->state.

Change-Id: I965012ceecbad7296fae4eff7d429dcb8391aa2c
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>