mhi: cntrl: qcom: remove boot monitor thread to use status cb

Remove the boot monitor thread and use the mission mode entry
callback instead to handle runtime pm enablement and boot
logger channel cleanup.

Change-Id: Ia018d51987d3201bc65223c3cdf7165d2f6da4ca
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>