Fix permissions for OmxILOsalPrm

@diego-ch
There's a permission error when stericsson blobs try to access those files
ie. playing media results on this error:

V/OmxILOsalPrm( 1833): ChangeResourceState(0, 50, 0x447e79f4)
E/OmxILOsalPrm( 1833): updateSocDvfsOpp - failed to open /dev/ape_opp
V/OmxILOsalPrm( 1833): ChangeResourceState(1, 50, 0x447e79f4)
E/OmxILOsalPrm( 1833): updateDDROpp - failed to open /dev/ddr_opp
V/OmxILOsalPrm( 1833): ChangeResourceState(2, 600, 0x447e79f4)

Changing user to media and group to system fixes the error