arm64/mm: Directly use ID_AA64MMFR2_EL1_VARange_MASK

Tools generated register fields have in place mask macros which can be used
directly instead of shifting the older right end sided masks.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
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/20230711092055.245756-1-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>