ipod6g: rename some target files

As preparation to add new targets to the s5l8702 directory,
rename files as:

s5l8702/ipod6g/*-ipod6g.c -> s5l8702/ipod6g/*-6g.c

Change-Id: I0cd03d6bcf39b2aa198235f9014cb6948bbafcd5
14 files changed