drivers: net: Mark functions as static in 3945-debug.c

This patch marks the function il3945_ucode_rx_stats_read(),
il3945_ucode_tx_stats_read() and il3945_ucode_general_stats_read() in
3945-debug.c as static because they are not used outside this file.

Thus, it also removes the following warnings in
wireless/iwlegacy/3945-debug.c:

drivers/net/wireless/iwlegacy/3945-debug.c:52:1: warning: no previous prototype for ‘il3945_ucode_rx_stats_read’ [-Wmissing-prototypes]
drivers/net/wireless/iwlegacy/3945-debug.c:317:1: warning: no previous prototype for ‘il3945_ucode_tx_stats_read’ [-Wmissing-prototypes]
drivers/net/wireless/iwlegacy/3945-debug.c:407:1: warning: no previous prototype for ‘il3945_ucode_general_stats_read’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>