IB/mthca: Fix printk format used for firmware version in warning

When warning about out-of-date firmware, current mthca code messes up
the formatting of the version if the subminor doesn't have three
digits.  It doesn't fill the field with 0s so we end up with:

    ib_mthca 0000:0b:00.0: HCA FW version 1.1.  0 is old (1.2.  0 is current).

Change the format from "%3d" to "%03d" to get the right thing printed.

Signed-off-by: Roland Dreier <rolandd@cisco.com>