arm64: cpufeatures: Correctly handle signed values

Although we've had signed values for some features such as PMUv3
and FP, the code that handles the comparaison with some limit
has a couple of annoying issues:

- the min_field_value is always unsigned, meaning that we cannot
  easily compare it with a negative value

- it is not possible to have a range of values, let alone a range
  of negative values

Fix this by:

- adding an upper limit to the comparison, defaulting to all bits
  being set to the maximum positive value

- ensuring that the signess of the min and max values are taken into
  account

A ARM64_CPUID_FIELDS_NEG() macro is provided for signed features, but
nothing is using it yet.

Signed-off-by: Marc Zyngier <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Oliver Upton <[email protected]>

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