drivers: ufs: Extend the delay after reset to wait for some slower chips

We've seen issues with some THG based UFS chips, where
after reset the LUNs don't always enumerate properly.

After some debugging, we found that extending the mdelay
here seems to resolve the issue by giving the chips enough
time to complete reset.

Change-Id: I848f810b2438ed6ad3d33db614c61d2cef9ac400
Signed-off-by: John Stultz <john.stultz@linaro.org>