ASoC: rockchip: Allocate enough memory so we don't overflow routes

In the recent commit d9f9c167 ("ASoC: rockchip: Init dapm routes
dynamically") we improperly allocated memory for the card->dapm_routes
causing us to overflow the allocation on every boot.  Oops.

Let's allocate the correct amount of memory.  We'll also add a check
to make sure that we don't overrun memory even if we encounter some
sort of weird device tree.

Fixes: d9f9c167 ("ASoC: rockchip: Init dapm routes dynamically")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>