target/ppc: Remove single-step suppression inside 0x100-0xf00

Single-step interrupts are suppressed if the nip is between 0x100 and
0xf00. This has been the case for a long time and it's not clear what
the intention is. Likely either an attempt to suppress trace interrupts
for instructions that cause an interrupt on completion, or a workaround
to prevent software tripping over itself single stepping its interrupt
handlers.

BookE interrupt vectors are set by IVOR registers, and BookS has AIL
modes and new interrupt types, so there are many interrupts including
the debug interrupt which can be outside this range. So any effect it
might have had does not cover most cases (including Linux on recent
BookS CPUs).

Remove this special case.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[ clg : fixed typo in commit logs ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

target/ppc/translate.c

@@ -7410,8 +7410,7 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, CPUState *cs)
     }
 
     /* Honor single stepping. */
-    if (unlikely(ctx->singlestep_enabled & CPU_SINGLE_STEP)
-        && (nip <= 0x100 || nip > 0xf00)) {
+    if (unlikely(ctx->singlestep_enabled & CPU_SINGLE_STEP)) {
         switch (is_jmp) {
         case DISAS_TOO_MANY:
         case DISAS_EXIT_UPDATE: