KVM: arm64: mmu: fix a kernel-doc warning

KVM: arm64: mmu: fix a kernel-doc warning

Use the correct function name in a kernel-doc comment to prevent
a warning:

arch/arm64/kvm/mmu.c:321: warning: expecting prototype for unmap_stage2_range(). Prototype was for __unmap_stage2_range() instead

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Zenghui Yu <yuzenghui@huawei.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.linux.dev
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20240117230714.31025-6-rdunlap@infradead.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>