USB: phy-msm: Don't use pm_runtime_put_sync while stopping host mode

Currently driver is using pm_runtime_put_sync() during stop host mode.
Due to this, USB enters low power mode immediately and results in
unnecessarily USB exiting & entering low power mode in B_IDLE state.
pm_runtime_autosuspend() doesn't put device in low power mode immediately
rather it starts autosuspend timer of autosuspend delay. This helps in
avoiding unnecessary exit and enter low power mode. Hence fix this by
using pm_runtime_autosuspend() after updating device busy time while
coming back to idle from host role.

Change-Id: I02c9d61685ab36bef830389839a9fc964acb2ae3
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>