ixgbe: Fix format string in ixgbe_fcoe.c

cppcheck detected following warning in ixgbe_fcoe.c
(warning) %d in format string (no. 1) requires 'int' but the
argument type is 'unsigned int'.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Tested-By: Jack <Morgan&lt;jack.morgan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>