mx5: iomux: add i.MX53 IOMUX definitions for iomux-v3 model

This adds the used pins for the Efika MX Slimbook only, as per the
original recommendation that we do not add pins nobody uses.

Signed-off-by: Matt Sealey <matt@genesi-usa.com>
efikamx: add Efika MX Slimbook to mach-types

Signed-off-by: Matt Sealey <matt@genesi-usa.com>
efikamx: add Efika MX Slimbook to the boards.cfg

Signed-off-by: Matt Sealey <matt@genesi-usa.com>
efikamx: add Efika MX Slimbook board support

The Efika MX Slimbook (a.k.a. the "Efika MX53") is a small (100mm x 50mm),
high-density, high-integration design around the Freescale i.MX53 SoC,
with a focus on cost-reduction. The board targets Netbook and Industrial
use cases with integrated LVDS panels and batteries.

This adds basic platform support including MMC, USB support and basic
booting as per Genesi's production boot model for U-Boot, as streamed
from the Housekeeping MCU on-board.

Signed-off-by: Matt Sealey <matt@genesi-usa.com>
efikamx: build with Thumb2 to save space

Signed-off-by: Matt Sealey <matt@genesi-usa.com>