ARM: imx: fix mx51 ehci setup errors

This patch completes commit 08406f54 by fixing the following issues, according to
the reference manual:
* MXC_OTG_UCTRL_OPM_BIT disables (masks) the power/oc pins if set, like H1PM and
  H2PM, not the opposite.
* MXC_OTG_PHYCTRL_OC_DIS_BIT disables the oc pin if set, like H1_OC_DIS, not the
  opposite.
* Typos in comments.

Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Arnaud Patard (Rtp) <arnaud.patard@rtp-net.org>
Cc: <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>