[PATCH v3 20/27] thunderbolt: Add support for NHI mailbox

The host controller includes two sets of registers that are used to communicate with the firmware. Add functions that can be used to access these registers. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet Signed-off-by:

[PATCH v3 20/27] thunderbolt: Add support for NHI mailbox

The host controller includes two sets of registers that are used to communicate with the firmware. Add functions that can be used to access these registers. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet Signed-off-by: Mika Westerberg