There is an error path, where iomemory is left mapped.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: NAlexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Alan Hourihane <alanh@fairlite.demon.co.uk>
Signed-off-by: NBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>