thunderbolt: Drop duplicated 0x prefix from format string

The tb_dbg() call is using %#x that already adds the 0x prefix so don't
duplicate it.

Fixes: 9039387e ("thunderbolt: Add USB4 router operation proxy for firmware connection manager")
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <YehezkelShB@gmail.com>