hw/intc/arm_gicv3: Fix writes to ICC_CTLR_EL3

hw/intc/arm_gicv3: Fix writes to ICC_CTLR_EL3

The ICC_CTLR_EL3 register includes some bits which are aliases
of bits in the ICC_CTLR_EL1(S) and (NS) registers. QEMU chooses
to keep those bits in the cs->icc_ctlr_el1[] struct fields.
Unfortunately a missing '~' in the code to update the bits
in those fields meant that writing to ICC_CTLR_EL3 would corrupt
the ICC_CLTR_EL1 register values.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190520162809.2677-5-peter.maydell@linaro.org