omap4-common: fix permissions for cpufreq/scaling_min_freq

this allow mediaserver to enable performance mode for OMAP4 USB Audio
which was overridden by init.cm.rc

Change-Id: Ie8be95b20786685708cb8a49c14d08454f2051dd
omap4-common: define BOARD_HAVE_PRE_KITKAT_AUDIO_BLOB

Change-Id: Ia697b592a5504d59e0e0867241013796d0b95aa9