Drop Freescale official Linux kernel for i.MX23, i.MX28 and i.MX5 SoC families

Drop Freescale official Linux kernel for i.MX23, i.MX28 and i.MX5 SoC families

The Linux kernel provided by Freescale for i.MX28 and i.MX5 is too old
(2.6.35.3) and there are no plans to upgrade it, as the OE-Core is
going to use GCC 5.2 as default compiler soon and it is not possible
to compile this kernel with the new toolchain, thus the removal.

The metadata related to the i.MX23, i.MX28 and i.MX5 SoC family, which
is dependant of this Linux kernel support, has been removed in this
commit so if someone ever wants to bring it back it is easy to find
out all the necessary changes. The recipes affected are:

 - alsa-state
 - amd-gpu-x11-bin
 - gtk+3
 - imx-lib
 - imx-test
 - imx-vpu
 - libfslcodec
 - linux-imx
 - mesa
 - qt4-embedded-free
 - qt4-x11-free
 - qtbase
 - xf86-video-imxfb

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Acked-by: Daiane Angolini <daiane.angolini@freescale.com>