mdss: display: add spin_lock to mdss_disable_irq_nosync()

Add spin_lock to mdss_lock inside mdss_disable_irq_nosync
to avoid race condition which can cause mdss_irq to be disabled
while irq_mask bits are still set.

CRs-Fixed: 624806
Change-Id: I44074a057dff49dfc7a4d2829f3c4e599dca4a69
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
msm: mdss: dsi: check ULPS state only for active lanes

It is possible that for certain panels, not all four data lanes are
active. After configuring the lanes to Ultra Low Power State (ULPS),
only check the status of the active lanes since the lanes that are not
used will never enter ULPS.

Change-Id: I0da358f2bd24d4472cfccb6cca9ca8b26ffa8226
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>