ASoC: bcm: cygnus-pcm: Fix unused assignment about 'rc'

Delete unused initialized value of 'rc', because it will
be assigned by the function devm_request_irq().

Signed-off-by: Zhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20210728124411.3168-1-tangbin@cmss.chinamobile.com


Signed-off-by: Mark Brown <broonie@kernel.org>