Change ethernet enabled state from int to using boolean

Previously, EthernetTracker uses int to store ethernet enabled state.
Since ethernet enabled state only has 2 possible values
(disabled/enabled), this patch simplified the state representation into
using boolean instead.

Bug: None
Test: atest EthernetManagerTest
Change-Id: Id0b2c8da244c3aa09cb20f2fb67078f2cb4cbe56
1 file changed