jfs: avoid -Wtautological-constant-out-of-range-compare warning again

jfs: avoid -Wtautological-constant-out-of-range-compare warning again

The comparison of an __s8 value against DTPAGEMAXSLOT is still trivially
true, causing a harmless (default disabled) warning with clang:

fs/jfs/jfs_dtree.c:4419:25: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
 4419 |                                         p->header.freelist >= DTPAGEMAXSLOT)) {
      |                                         ~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~

I previously worked around two of these in commit 7833570dae83 ("jfs: avoid
-Wtautological-constant-out-of-range-compare warning"), but now a new one has
come up, so address the same way by dropping the redundant range check.

Fixes: 119e448bb50a ("jfs: add dtpage integrity check to prevent index/pointer overflows")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>