bus: mhi: host: Notify EE change via uevent

Notify the MHI device's Execution Environment (EE) state via uevent,
enabling applications to receive real-time updates and take appropriate
actions based on the current state of MHI.

Signed-off-by: Vivek Pernamitta <quic_vpernami@quicinc.com>
[mani: Reworded subject, removed error print, fixed indentation]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Link: https://patch.msgid.link/20250912-b4-uevent_vdev_next-20250911-v2-1-89440407bf7e@quicinc.com