CI: move stm32mp157c-dk2 to be alphabetical

Trivial change to move stm32mp157c-dk2 to its alphabetical location.
This is relevant because it aligns the file to match the order on the
gilab pipeline entry.

Signed-off-by: Jon Mason <jon.mason@arm.com>
Signed-off-by: Naveen Saini <naveen.kumar.saini@intel.com>