vxge: ensure data0 is initialized in when fetching firmware version information

Currently variable data0 is not being initialized so a garbage value is
being passed to vxge_hw_vpath_fw_api and this value is being written to
the rts_access_steer_data0 register.  There are other occurrances where
data0 is being initialized to zero (e.g. in function
vxge_hw_upgrade_read_version) so I think it makes sense to ensure data0
is initialized likewise to 0.

Detected by CoverityScan, CID#140696 ("Uninitialized scalar variable")

Fixes: 8424e00d ("vxge: serialize access to steering control register")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>