bus: mhi: host: Update mhi driver description

This should be a mistake. MHI contains "Host Interface"
already. So we shall update "MHI" to "Modem" and the full
name shall be "Modem Host Interface".

Signed-off-by: Slark Xiao <slark_xiao@163.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20221229011358.15874-1-slark_xiao@163.com


Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>