bus: mhi: core: Remove pre_init flag used for power purposes

Some controllers can choose to skip preparation for power up.
In that case, device context is initialized based on the pre_init
flag not being set during mhi_prepare_for_power_up(). There is no
reason MHI host driver should maintain and provide controllers
with two separate paths for preparing MHI.

Going forward, all controllers will be required to call the
mhi_prepare_for_power_up() API followed by their choice of sync
or async power up. This allows MHI host driver to get rid of the
pre_init flag and sets up a common way for all controllers to use
MHI. This also helps controllers fail early on during preparation
phase in some failure cases.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617313309-24035-1-git-send-email-bbhatt@codeaurora.org


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