staging: et131x: Remove send_hw_lock spinlock

We don't need to use this lock - the tx path is protected by the
networking subsystem xmit_lock, so we don't also need it in
nic_send_packet().

The other use of this spinlock in et1310_enable_phy_coma() to protect
a low power flag makes no sense, so can just be removed.

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>