ASoC: wm_adsp: Limit firmware control name to ALSA control name size

ALSA only supports control names up to 44 bytes, so there is no point
allocating a whole page of memory to hold the control name, just limit
the control name to 44 bytes.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>