cmd: upl: correct printf code

cmd: upl: correct printf code

Building on 32-bit results in a build failure:

    cmd/upl.c:75:51: warning: format ‘%lx’ expects argument of type
    ‘long unsigned int’, but argument 3 has type ‘size_t’
    {aka ‘unsigned int’} [-Wformat=]
    75 | printf("UPL handoff written to %lx size %lx\n", addr, abuf_size(&buf));
       |                                         ~~^           ~~~~~~~~~~~~~~~
       |                                           |           |
       |                                           |           size_t {aka unsigned int}
       |                                           long unsigned int
       |                                         %x

Fixes: 264f4b0b34c0 ("upl: Add a command")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Neha Malcom Francis <n-francis@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>