SeaMicro to use the new ManagementInterface

Add the new ManagementInterface to the SeaMicro driver promoting the
set_boot_device() method from the VendorPassthru to the new interface.

The test_set_boot_device_no_input() test was removed because now inputting
a device is part of the function declaration.

Implements: blueprint new-management-interface
Change-Id: I2c5d0bba9045ce27c6b81ddefb6ca6bb019f2991
Merge "SeaMicro to use the new ManagementInterface"