MFC r348377-r348379, r349347

r348377:
gic_v3: consolidate per-cpu redistributor information

Update 'struct gic_redists' to consolidate all per-cpu redistributor
information into a new 'struct redist_pcpu'. Provide a new interface
(GICV3_IVAR_REDIST) for the GIC driver, which can be used to retrieve
the per-cpu data.

This per-cpu redistributor struct will be later used to improve the
GIC ITS setup.

While there, remove some unused fields in gic_v3_var.h interface.
No functional changes.

Reviewed by: andrew
Differential Revision: https://reviews.freebsd.org/D19842

r348378:
gicv3_its: refactor LPI init into a new function

Move the per-cpu LPI intialization to a separate function. This is
in preparation for a commit that does LPI init only once for a CPU,
even when there are multiple ITS blocks associated with the CPU.

No functional changes in this commit.

Reviewed by: andrew
Differential Revision: https://reviews.freebsd.org/D19843

r348379:
gicv3_its: do LPI init only once per CPU

The initialization required for LPIs (setting up pending tables etc.)
has to be done just once per CPU, even in the case where there are
multiple ITS blocks associated with the CPU.

Add a flag lpi_enabled in the per-cpu distributor info for this and
use it to ensure that we call its_init_cpu_lpi() just once.

This enables us to support platforms where multiple GIC ITS blocks
can generate LPIs to a CPU.

Reviewed by: andrew
Differential Revision: https://reviews.freebsd.org/D19844

r349347:
arm64 gicv3_its: enable all ITS blocks for a CPU

We now support multiple ITS blocks raising interrupts to a CPU.
Add all available CPUs to the ITS when no NUMA information is
available.

This reverts the check added in r340602, at that tim we did not
suppport multiple ITS blocks for a CPU.

Differential Revision: https://reviews.freebsd.org/D20417