arm64: cpufeature: Remove cpu_has_fwb() check

cpu_has_fwb() is supposed to warn user is following architectural
requirement is not valid:

LoUU, bits [29:27] - Level of Unification Uniprocessor for the cache
                     hierarchy.

  Note

    When FEAT_S2FWB is implemented, the architecture requires that
    this field is zero so that no levels of data cache need to be
    cleaned in order to manage coherency with instruction fetches.

LoUIS, bits [23:21] - Level of Unification Inner Shareable for the
                      cache hierarchy.

  Note

    When FEAT_S2FWB is implemented, the architecture requires that
    this field is zero so that no levels of data cache need to be
    cleaned in order to manage coherency with instruction fetches.

It is not really clear what user have to do if assertion fires. Having
assertions about the CPU design like this inspire even more assertions
to be added and the kernel definitely is not the right place for that,
so let's remove cpu_has_fwb() altogether.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Link: https://lore.kernel.org/r/20220224164739.119168-1-vladimir.murzin@arm.com


Signed-off-by: Will Deacon <will@kernel.org>