iwlegacy: convert hex_dump_to_buffer() to %*ph

There is no need to use hex_dump_to_buffer() in the cases like this:

	hexdump_to_buffer(buf, len, 16, 1, outbuf, outlen, false);	/* len <= 16 */
	sprintf("%s\n", outbuf);

since it maybe easily converted to simple:

	sprintf("%*ph\n", len, buf);

Note: it seems in the case the output is groupped by 2 bytes and looks like a
typo. Thus, patch changes that to plain byte stream.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>