The EQ enabled setting needs to call into the DSP core when it's
changed but this was only hooked into the EQ menu. The quickscreen
uses option_select_next_val() so those DSP hooks were not getting
called because the setting did not have any callback defined.
It seems this bug was introduced by 362f7a3220 removing the blanket
call to settings_apply(). Other settings might be affected too.
Change-Id: Idcce5809c525fa619e6bdf1be50c98a5df103fec