ARM: imx: Remove mxc specific ulpi access ops

There are ulpi access ops implemented in drivers/usb/phy/phy-ulpi.c.
mxc access ops implement the same access operations within mach-imx. This
patch removes the mxc ulpi file and uses phy-ulpi instead for
imx_otg_ulpi_create.

phy-ulpi successfully tested with i.MX27 Phytec phyCARD-S (pca100).

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>