cxgb4vf: make a couple of functions static

The functions t4vf_link_down_rc_str and t4vf_handle_get_port_info are
local to the source and do not need to be in global scope, so make
them static.

Cleans up sparse warnings:
symbol 't4vf_link_down_rc_str' was not declared. Should it be static?
symbol 't4vf_handle_get_port_info' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>