ARM: gic: add missing distributor defintions

Add missing register map offsets for the distributor and rename
GIC_DIST_ACTIVE_BIT to GIC_DIST_ACTIVE_SET to be consistent.

Cc: Marc Zyniger <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
KVM: ARM: vgic: Use defines instead of hardcoded numbers.

Address reviewer comments.

Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
KVM: ARM: vgic: Define VGIC_MAX_LRS

Define maximum number of link registers we can handle instead of using
literals in the code.  If an architecture reports more link registers
than we support, only use the number we can support.

Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>