Don't allow tdata2 to be smaller for address matches.

This led to endless discussion about what happens when matching invalid
addresses. This is on the critical path for Architectural Review
approval, which is more important than allowing an implementation to
save a few gates on triggers that match on addresses but not on data.

introduction.tex

@@ -236,6 +236,8 @@ \subsubsection{Incompatible Changes During 1.0 Stable}
 the {\tt progbuf} registers. \PR{731}
 \item \RcsrTcontrol fields apply to all traps, not just breakpoint traps. This
     reverts \PR{723}. \PR{880}
+\item \RcsrTdataTwo cannot be limited to only holding addresses, even if only
+addresses can be matched. \PR{919}
 \end{steps}
 
 \section{About This Document}

xml/hwbp_registers.xml

@@ -310,12 +310,6 @@
         Table~\ref{tab:hwbp_timing}, both timings should be supported on load
         address triggers.
 
-        This trigger type may be limited to address comparisons (\FcsrMcontrolSelect is
-        always 0) only. If that is the case and masking is not supported (match
-        values 4, 5, 12, 13), then \RcsrTdataTwo must be able to
-        hold all valid virtual addresses but it need not be capable of holding
-        other values.
-
         The Privileged Spec says that breakpoint exceptions that occur on
         instruction fetches, loads, or stores update the {\tt tval} CSR
         with either zero or the faulting virtual address.  The faulting
@@ -667,12 +661,6 @@
         A chain of triggers must only fire if every trigger in the chain was
         matched by the same instruction.
 
-        This trigger type may be limited to address comparisons (\FcsrMcontrolSixSelect is
-        always 0) only. If that is the case and masking is not supported (match
-        values 4, 5, 12, 13), then \RcsrTdataTwo must be able to
-        hold all valid virtual addresses but it need not be capable of holding
-        other values.
-
         The Privileged Spec says that breakpoint exceptions that occur on
         instruction fetches, loads, or stores update the {\tt tval} CSR
         with either zero or the faulting virtual address.  The faulting