The IPA code now uses the generic remoteproc SSR notification
mechanism.  This makes the original IPA notification code unused
and unnecessary, so get rid of it.

This is effectively a revert of commit d7f5f3c8 ("remoteproc:
add IPA notification to q6v5 driver").
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20200724181142.13581-3-elder@linaro.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>