Remove now-unused cheri_tsc_hack: we now have per-thread trusted stacks
so don't require the global one introduced during early testing.

Wherever we report a hex value in kernel CHERI debug output, preceed it
with an '0x', as although we were quite consistent in using hex, it was
potentially confusing (I certainly got confused, anyway).

Print out $c4 as well when dumping capability information to the console
following an application CP2 fault.