arm64: Use Signed/Unsigned enums for TGRAN{4,16,64} and VARange

Open-coding the feature matching parameters for LVA/LVA2 leads to
issues with upcoming changes to the cpufeature code.

By making TGRAN{4,16,64} and VARange signed/unsigned as per the
architecture, we can use the existing macros, making the feature
match robust against those changes.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>