move store capability to tag clearing if the store cap permission isn't set

[tariqkurd-repo]

Load capability clears the tag on the loaded data if permit_load_cap is not set.
Store capability takes an exception, can it be made symmetrical with load capability and store a zero tag to memory if permit_store_cap is not set?

Otherwise it is (AFAIK) the only example of a data-dependant store violation.

[jrtc27]

This is an open question. Look out for the Morello performance report that is imminent (awaiting approval), which is relevant to this discussion.