target: rename splash screen display configuration functions

Display initialization and shutdown functions for specific MSM targets
are defined in the corresponding target folders.  However, these
functions share the same name as the generic display_init and
display_shutdown function defined as the platform level api.
Rename these to target_display_init and target_display_shutdown to
be in line with the other target specific APIs.

Change-Id: I63797952182315f1006e22ec47e08a25a786daa4
14 files changed