arm64: mvebu: Rename the db-88f3720 to armada-37xx platform

Modify the file names and deifinitions relater to Marvell
db-77f3720 board support. Convert these names to more generic
armada-37xx platform for future addition of more boards
based on the same SoC family.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Igal Liberman <igall@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/configs/mvebu_db-88f3720_defconfig b/configs/mvebu_db-88f3720_defconfig
index 80f2599..4286695 100644
--- a/configs/mvebu_db-88f3720_defconfig
+++ b/configs/mvebu_db-88f3720_defconfig
@@ -1,7 +1,7 @@
 CONFIG_ARM=y
 CONFIG_ARCH_MVEBU=y
 CONFIG_SYS_MALLOC_F_LEN=0x2000
-CONFIG_TARGET_MVEBU_DB_88F3720=y
+CONFIG_TARGET_MVEBU_ARMADA_37XX=y
 CONFIG_DEFAULT_DEVICE_TREE="armada-3720-db"
 CONFIG_AHCI=y
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set