post_proc: reverb: send reverb params to DSP when effect is enabled

Reverb effect is not getting enabled in DSP when client sets the preset
first and then enables the effect. reverb_enable call only sets the
enable flag and does not set the required params on DSP. This happens
in case of pcm offload playback. process_chain_l from playback thread
loop triggers the enable call on the respective effect and this call
need not always be set before any setParam call on the effect.

Fix is to enable in DSP as well when reverb is enabled by the user
and a valid preset is set. This way the order of setting preset and
enabling effect is not restricted

CRs-Fixed: 1056205

Change-Id: Ia4523e87537f174782727a05b356f21f42de1abf