ASoC: cs35l35: Add IRQF_SHARED to IRQ flags

As it is quite common to use a stereo pair of amps but share the IRQ
line between them both add the IRQF_SHARED flag whilst requesting
cs35l35's IRQ.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Brian Austin <brian.austin@cirrus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>