staging:iio: use ida_simple_get and ida_simple_remove + merge ids

Use new simple ida allocation functions to remove some boilerplate
code.

Also, now we only have one chdev per device we don't need to maintain
a separate ida for minor numbers. Just use the devices id.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
hwmon: convert idr to ida and use ida_simple interface

hwmon was using an idr with a NULL pointer, so convert to an
ida which then allows use of Rusty's ida_simple_get.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:
	drivers/hwmon/hwmon.c

Change-Id: I2ba78072319ddbbfc2029f6c5762479183c95c40

Conflicts:
	drivers/hwmon/hwmon.c