msm: mhi_dev: Modify sending completion command

Sending completion command after suspend or resume
to the host is redundant and not defined in the modem
host interface specification.

Change-Id: I4be43e37a8f131ce706c0d57d629d9298d16711d
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>