drivers/net/wireless/b43: fix sparse warnings: make symbols static

Fix this sparse warnings:

  drivers/net/wireless/b43/phy_a.c:80:6: warning: symbol 'b43_radio_set_tx_iq' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_a.c:150:6: warning: symbol 'b43_radio_init2060' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:57:10: warning: symbol 'b43_radio_channel_codes_bg' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:218:6: warning: symbol 'b43_set_txpower_g' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:386:6: warning: symbol 'b43_nrssi_hw_write' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:393:5: warning: symbol 'b43_nrssi_hw_read' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:404:6: warning: symbol 'b43_nrssi_hw_update' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:418:6: warning: symbol 'b43_nrssi_mem_update' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:592:6: warning: symbol 'b43_calc_nrssi_slope' was not declared. Should it be static?
  drivers/net/wireless/b43/phy_g.c:1357:5: warning: symbol 'b43_radio_init2050' was not declared. Should it be static?

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>