iwl_dbgfs_fh_reg_read() can cause crashes and/or
BUG_ON in slub because the ifdefs are wrong, the
code in iwl_dump_fh() should use DEBUGFS, not
DEBUG to protect the buffer writing code.
Also, while at it, clean up the arguments to the
function, some code and make it generally safer.
Cc: stable@vger.kernel.org Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>