KVM: arm64: Expose KVM_ARM_VCPU_REC to user space

Increment KVM_VCPU_MAX_FEATURES to expose the new capability to user
space.

Signed-off-by: Steven Price <steven.price@arm.com>
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*NOTE*: This also exposes KVM_ARM_VCPU_HAS_EL2/KVM_ARM_VCPU_HAS_EL2_E2H0
(as they are both less than KVM_ARM_VCPU_REC) - so this currently
depends on nested virt being 'finished' before merging.

So this should be merged after: "KVM: arm64: Allow userspace to request
KVM_ARM_VCPU_EL2*":
https://lore.kernel.org/r/20250408105225.4002637-17-maz%40kernel.org