net: e1000e: solve insmod 'Unknown symbol mutex_lock' error

After I turn on the CONFIG_LOCK_STAT=y, insmod e1000e.ko will report:
[    5.641579] e1000e: Unknown symbol mutex_lock (err -2)
[   90.775705] e1000e: Unknown symbol mutex_lock (err -2)
[  132.252339] e1000e: Unknown symbol mutex_lock (err -2)

This problem fixed after include <linux/mutex.h>.

Signed-off-by: Hao Chen <chenhaoa@uniontech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>