imx: fix iomux v3

Commit "ARM: i.MX IOMUX-V3 replace struct pad_desc with bitmapped cookie"
(b705cb4d42e95a4a43a8945571c8613e71526c3d) introduced a typo which was
preventing my efikamx to boot. This patch is fixing that.

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>