IB/ipath: Fix PCI config write size used to clear linkctrl error bits

In slave_or_pri_blk(), pci_write_config_byte() is used to write a
16-bit quantity to clear linkctrl CRC error bits.  This is clearly a
bug and also causes the warning

    drivers/infiniband/hw/ipath/ipath_iba6110.c: In function 'slave_or_pri_blk':
    drivers/infiniband/hw/ipath/ipath_iba6110.c:849: warning: overflow in implicit constant conversion

Fix this by using pci_write_config_word() instead.

Acked-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>