net: ipa: explicitly disallow inter-EE interrupts

It is possible for other execution environments (EEs, like the modem)
to request changes to local (AP) channel or event ring state.  We do
not support this feature.

In gsi_irq_setup(), explicitly zero the mask that defines which
channels are permitted to generate inter-EE channel state change
interrupts.  Do the same for the event ring mask.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>