arm64/mm: Make vmemmap_free() available only with CONFIG_MEMORY_HOTPLUG

arm64/mm: Make vmemmap_free() available only with CONFIG_MEMORY_HOTPLUG

vmemmap_free() callsites (mm/sparse.c) and declaration (include/linux/mm.h)
are protected with CONFIG_MEMORY_HOTPLUG. This function is not required if
CONFIG_MEMORY_HOTPLUG is not enabled. Hence move the config wrapper outside
the function definition.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/1621842030-23256-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>