commit 3e78080f upstream.

Not having power is a pretty serious error so check that we are able to
enable the supply and error out if we can't.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[bwh: Backported to 3.2: driver does not use the devm API to manage
 memory, so goto err_free_data rather than returning on error]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>