[1/2] smdk4412-common: overlay cleanup

i9300: https://gerrit.omnirom.org/#/c/2778
n7100: https://gerrit.omnirom.org/#/c/3135
n7105: https://gerrit.omnirom.org/#/c/3136

PS:
- default screen timeout to 1 minute
- volume rocker show is set to true on the actual config; not needed

Change-Id: I5da2ae06f7835fe13bc786ae088aa739c5156e86