configs/freescale_imx8mmevk: update codeaurora URLs to github

configs/freescale_imx8mmevk: update codeaurora URLs to github

NXP moved all its open source code repositories from Code Aurora Forum
to github. See for example:
https://github.com/nxp-imx/meta-imx/commit/39bc4d81969a40e0da660519cf4ed083b9c53097

Software packages are now grouped in several NXP github
projects/organizations (nxp-imx, nxp-qoriq, ...). See:
https://www.nxp.com/design/software/embedded-software/nxp-github:NXP-GITHUB

The NXP code published on Code Aurora is still present (at the time of
this commit) but is no longer receiving updates. It is also expected
to be shut down on 2023-03-31. The Code Aurora website
https://source.codeaurora.org/ currently show the following message:
"""
Note: Qualcomm Innovation Center Inc. maintained repositories have
migrated to git.codelinaro.org. QUIC repositories on this site will
not receive any updates after March 31, 2022, and will be deleted on
March 31, 2023. If your project depends on these repositories, please
adjust your tooling configuration to use the new, up-to-date project
location.
"""

For this reason, the NXP recipes using codeaurora.org urls need to be
updated to the correct github.com replacement.

Note: this commit does not change the component version. Only the
download URL is updated. The archive content is expected to be the
same.

Note 2: this commit updates the Kernel, U-Boot and ATF download urls.
The method is also changed from _CUSTOM_GIT to _CUSTOM_TARBALL.

Signed-off-by: Julien Olivain <[email protected]>
Signed-off-by: Yann E. MORIN <[email protected]>