staging:iio:ad799x fix error_free_irq which was freeing an irq that may not have been requested

Only free an IRQ in error_free_irq, if it has been requested previously.

Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: stable@vger.kernel.org
1 file changed