MMU: Remove software-loaded dTLB mode

This removes the hack where the tlbie instruction could be used to
load entries directly into the dTLB, because we don't report the
correct DSISR values for accesses that hit software-loaded dTLB
entries and have privilege or permission errors.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

dcache.vhdl

@@ -586,8 +586,6 @@ begin
             if r0_valid = '1' and r0.tlbie = '1' then
                 if r0.req.addr(11 downto 10) /= "00" then
                     tlbia := '1';
-                elsif r0.req.addr(9) = '1' then
-                    tlbwe := '1';
                 else
                     tlbie := '1';
                 end if;