net: e1000: Remove unused declarations

Commit 675ad473 ("e1000: Use netdev_<level>, pr_<level> and dev_<level>")
declared but never implemented e1000_get_hw_dev_name().
Commit 1532ecea ("e1000: drop dead pcie code from e1000")
removed e1000_check_mng_mode()/e1000_blink_led_start() but not the declarations.
Commit c46b59b2 ("e1000: Remove unused function e1000_mta_set.")
removed e1000_mta_set() but not its declaration.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>