mmc: sdhci-msm: Don't turnoff Vcc during initialization

As per emmc specification, device should be notified either with
power-off or sleep notification before turning off the Vcc.
Failing to do so might affect the device longevity.

In mmc driver initialization phase even before device probing
gets completed, Vcc is getting turned off without these notifications.
Since it can't send commands at this stage, So just ensure that Vcc
is not turned off till initialization gets completed.

Change-Id: I0bbf0077357d66c888147be40a0c5d312b9ce063
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>