ASoC: pcm: Fix lack of platform bespoke_trigger() call

When the platform driver has no ops, the platform function
bespoke_trigger() is no more called.

The problem was introduced by the commit c5914b0a
	"ASoC: pcm: Check for ops before deferencing them"

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mark Brown <broonie@linaro.org>