net: micrel: Staticize local functions

These local functions are used only in this file.
Fix the following sparse warnings:

drivers/net/ethernet/micrel/ks8842.c:708:6: warning: symbol 'ks8842_handle_rx' was not declared. Should it be static?
drivers/net/ethernet/micrel/ks8842.c:718:6: warning: symbol 'ks8842_handle_tx' was not declared. Should it be static?
drivers/net/ethernet/micrel/ks8842.c:727:6: warning: symbol 'ks8842_handle_rx_overrun' was not declared. Should it be static?
drivers/net/ethernet/micrel/ks8842.c:735:6: warning: symbol 'ks8842_tasklet' was not declared. Should it be static?
drivers/net/ethernet/micrel/ks8851_mll.c:691:6: warning: symbol 'ks_enable_qmu' was not declared. Should it be static?

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>