arm_gicv3_kvm: Fix compile warning

Fix the following warning:

/home/pranith/qemu/hw/intc/arm_gicv3_kvm.c:296:17: warning: logical not is only applied to the left hand side of this bitwise operator [-Wlogical-not-parentheses]
            if (!c->gicr_ctlr & GICR_CTLR_ENABLE_LPIS) {
                ^             ~
/home/pranith/qemu/hw/intc/arm_gicv3_kvm.c:296:17: note: add parentheses after the '!' to evaluate the bitwise operator first
            if (!c->gicr_ctlr & GICR_CTLR_ENABLE_LPIS) {
                ^
/home/pranith/qemu/hw/intc/arm_gicv3_kvm.c:296:17: note: add parentheses around left hand side expression to silence this warning
            if (!c->gicr_ctlr & GICR_CTLR_ENABLE_LPIS) {
                ^

This logic error meant we were not setting the PTZ
bit when we should -- luckily as the comment suggests
this wouldn't have had any effects beyond making GIC
initialization take a little longer.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Message-id: 20170829173226.7625-1-bobby.prani@gmail.com
Cc: qemu-stable@nongnu.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>