iio: core: fix ptr_ret.cocci warnings

drivers/iio/industrialio-sw-trigger.c:169:1-3: WARNING: PTR_ERR_OR_ZERO can be used

 Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Octavian Purdila <octavian.purdila@intel.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Adriana Reus <adriana.reus@intel.com>
Cc: Daniel Baluta <daniel.baluta@intel.com>
Cc: Cristina Opriceana <cristina.opriceana@gmail.com>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/iio/industrialio-sw-trigger.c

@@ -167,9 +167,7 @@ static int __init iio_sw_trigger_init(void)
 		configfs_register_default_group(&iio_configfs_subsys.su_group,
 						"triggers",
 						&iio_triggers_group_type);
-	if (IS_ERR(iio_triggers_group))
-		return PTR_ERR(iio_triggers_group);
-	return 0;
+	return PTR_ERR_OR_ZERO(iio_triggers_group);
 }
 module_init(iio_sw_trigger_init);