print_mac() used many most net drivers and format_addr() used by
net-sysfs.c are very similar and they can be intergrated.
format_addr() is also identically redefined in the qla4xxx iscsi
driver.
Export a new function sysfs_format_mac() to be used by net-sysfs,
qla4xxx and others in the future. Both print_mac() and
sysfs_format_mac() call _format_mac_addr() to do the formatting.
Changed print_mac() to use unsigned char * to be consistent with
net_device struct's dev_addr. Added buffer length overrun checking
as suggested by Joe Perches.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
