KVM: arm64: Expose KVM_ARM_VCPU_REC to user space

Increment KVM_VCPU_MAX_FEATURES to expose the new capability to user
space.

*NOTE*: This also exposes KVM_ARM_VCPU_HAS_EL2 (as it is one less than
KVM_ARM_VCPU_REC) - so this currently depends on nested virt being
'finished' before merging. See below for discussion:

https://lore.kernel.org/r/a7011738-a084-46fa-947f-395d90b37f8b%40arm.com



Signed-off-by: Steven Price <steven.price@arm.com>