iwlwifi: fix TLV fragment allocation loop

iwlwifi: fix TLV fragment allocation loop

In the allocation loop, "pages" will never become zero (because of the
DIV_ROUND_UP), so if we can't allocate any size and pages becomes 1,
we will keep trying to allocate 1 page until it succeeds.  And in that
case, as coverity reported, block will never be NULL.

Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1487402 ("Control flow issues")
Fixes: 14124b25780d ("iwlwifi: dbg_ini: implement monitor allocation flow")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Fixes: 14124b25780d ("iwlwifi: dbg_ini: implement monitor allocation flow")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>