arm64/mm: Remove CONT_RANGE_OFFSET

arm64/mm: Remove CONT_RANGE_OFFSET

The macro was introduced by commit <ecf35a237a85> ("arm64: PTE/PMD
contiguous bit definition") at the beginning. It's only used by
commit <348a65cdcbbf> ("arm64: Mark kernel page ranges contiguous"),
which was reverted later by commit <667c27597ca8>. This makes the
macro unused.

This removes the unused macro (CONT_RANGE_OFFSET).

Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200910095936.20307-1-gshan@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>