ASoC: wm8996: Remove spurious IRQF_ONESHOT flag

This reverts ed043aeb ("ASoC: wm8996: Pass the IRQF_ONESHOT flag").

The coccinelle warnings is false positive because the original code does
set IRQF_ONESHOT by "trigger |= IRQF_ONESHOT;".

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>