ARM: imx: change static io mapping to use a function

Now only the virtual addresses [0xf4000000, 0xf5ffffff] are used for
static per-SoC mappings.  The few mappings of whole chip selects are
moved accordingly.

The now wrong defines for virtual base addresses are removed.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>