boards: renesas: Edit rcar_salvator_xs full_name

Edit the rcar_salvator_xs board full_name
from specific A57 name to generic one
to meet names used by other rcar boards
and unify this boards range documentation.

Signed-off-by: Aymeric Aillet <aymeric.aillet@iot.bzh>

Author: aaillet

boards/renesas/rcar_salvator_xs/board.yml

@@ -1,6 +1,6 @@
 board:
   name: rcar_salvator_xs
-  full_name: R-CAR Salvator XS M3 ARM CA57 (ARMv8)
+  full_name: R-Car Salvator-XS
   vendor: renesas
   socs:
   - name: r8a77961