bus: mhi: core: Introduce helper function to check device state

bus: mhi: core: Introduce helper function to check device state

Introduce a helper function to determine whether the device is in a
powered ON state and resides in one of the active MHI states. This will
allow for some use cases where access can be pre-determined.

Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20200929175218.8178-8-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>