[kernel][dev][gic] convert C to C++

Fairly minimal logical for conversion
Reduce the amount of CDECLS for internal routines
clang-format result

Largest change was the removal of a shadowed register in gicv2 which was
apparently unused.

Tested: validated that both gicv2 and gicv3 work in qemu

Change-Id: Ic5be6eec96b2fb02693f90dfa7eac9926a1c57ae

[arm][boot-shim][qemu] try to detect the GIC version from the device tree

-Filters out the appropriate gic information from the ZBI pass through
based on the gic version detected in the device tree.
-Extend the GICv3 driver to also initialize the pci bus driver, claiming
no MSI support

Change-Id: Ie75f48d94825c52b441ac0531f64cec3870d8835
Tested: Boot on qemu with either GIC version set.

[arm64][gicv2][gicv3] Fix base of software generated interrupts

mp_ipi_t interrupts are software generated and must be in the SGI
range (0-15). To ensure this, ipi_base must be <= 12.

Add helper function to validate SGI range at registration time.

Tested: Booted arm64 qemu with GICv2 and GICv3.

ZX-2285 #done

ZX-2302 #comment prereq

Change-Id: Ib1399478066a8dc17e5ef3caa026166ef12d588f

[kernel][arm64] Remove remaining use of MDI from the arm64 kernel

Kernel drivers are now configured via bootdata passed from the boot shims.

Change-Id: I056b9b2c74a99226d98416b0308480b85460e918

[kernel][gic] GIC code refactoring to add support for GICv3 in Hypervisor

Change-Id: Ia3e96db67ca507a26fbf537d8eb004c1d5a9b6b0