u-boot: Rename table from fslc to default

The table is better shown as a list of default
version and providers of u-boot, instead of a list
of have/don't have support on mainline u-boot for
each board.

Added 2 providers and a very small description for
each.

Signed-off-by: Daiane Angolini <angolini@gmail.com>
linux: Parameterize linux version

Add new linux providers to list of providers.

Signed-off-by: Daiane Angolini <angolini@gmail.com>
linux: Change linux-imx.inc to linux-defaulf.inc

It makes more sense to have a table to show the
default linux version for each board than have
the description of each possible kernel version.

Signed-off-by: Daiane Angolini <angolini@gmail.com>
kernel-linux: use the parameterized fslc version

Signed-off-by: Daiane Angolini <angolini@gmail.com>