drm/msm/sde: fixup sde_kms shutdown sequence and naming

Improve sde kms error detection and handling during
initialization.

Make naming of functions consistent within sde_kms file.

Change-Id: Ia8946752e7d89d811a46cd4725b2e43e02b9fd39
Signed-off-by: Lloyd Atkinson <latkinso@codeaurora.org>