ethernet: sun: add missing semicolon, fix build

Fix for this build problem:

drivers/net/ethernet/sun/ldmvsw.c: In function 'vsw_alloc_netdev':
drivers/net/ethernet/sun/ldmvsw.c:243:2: error: expected ';' before 'sprintf'
  sprintf(dev->name, "vif%d.%d", (int)handle, (int)port_id);
  ^~~~~~~

Fixes: a7639279

 ("ethernet: sun: remove direct netdev->dev_addr writes")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20211011173424.7743035d@canb.auug.org.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>