arm64: dts: ti: Makefile: Rearrange entries alphabetically

Entries are first grouped as per SoC present on the board. Groups are
sorted alphabetically. This makes it easy to know SoC to board mapping
and also add new entries in alphabetical order.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20230126071159.2337584-1-vigneshr@ti.com