[DRIVERS] Porting Freescale i.MX pin control driver.

This driver is required by the i.MX ESDHCI driver.
[DRIVERS] Freescale eSDHC i.MX controller driver.

Freescale eSDHC i.MX controller driver ported, with the generic GPIO
card-detect helper.
[DRIVERS] Correcting the Allwinner A10 pinctrl driver description.
[ARM] i.MX uSDHC device definitions added in the device tree.

i.MX uSDHC device definitions have been added, defining the 4 controllers,
and specifying that the 3rd and 4th are used by the i.MX Sabrelite.

The required GPIO group 2 and 7 definitions, and uSDHC IO mux have also been
added.
[CORE] Device tree function to check a node status added.

A device tree function to check a node status, returning VMM_ENODEV if it is
set to "disabled".
[DRIVERS] Avoid probing disabled i.MX SPI controllers.
[DRIVERS] Avoid probing disabled i.MX uSDHCI controllers.
[DRIVERS] Correcting the m25p80 device node matching.
[DRIVERS] Correcting and improving the i.MX GPIO base offset.

The GPIO base offset was set to 0. It must be left to -1, for the GPIO lib to
find an empty GPIO description place, or correctly set.
Instead of using the GPIO lib offset finding, the GPIO base as been set from
the controller physical address, defined in the device tree.
GPIO group 1 is set in the "gpio_desc" structure from 0 to 31, GPIO group 2
from 32 to 63, GPIO group 3 from 64 to 95 and so on.