staging:iio: trigger fixes for repeat request of same trigger and allocation failure

commit 5dd72ecb0166498852705939163f375d693d37f3 upstream.

Both of these are decidedly silly bugs show up whilst testing
completely different code paths.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --cc drivers/staging/iio/industrialio-trigger.c
Simple merge