msm: mdss: Change IOMMU map sequence for splash

Currently PA to VA mapping is not working with existing
sequence. Correct the sequence as below:

- set DOMAIN_ATTR_EARLY_MAP  attr to 1
- attach iommu
- perform mapping
- set DOMAIN_ATTR_EARLY_MAP to 0

Change-Id: Ieabb91cc69641bb41ca5a3ff5783dd55385490e6
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>