siemens,am335x: clean-up draco targets

Draco is a family of 3 boards: thuban, rastaban & etamin. Rename all
targets of the family adding the draco- prefix to increase readibility
and simplify future commits about concerning all boards of the family.

The name draco was initially used for the first target. It's deprecated
since a 2nd target was introduced. Unfortunately the draco target was
copied to the thuban target instead to be renamed. Remove it to save
unnecessary maintenance effort.

Signed-off-by: Enrico Leto <enrico.leto@siemens.com>
diff --git a/board/siemens/draco/Kconfig b/board/siemens/draco/Kconfig
index 1eb8a48..0cdf5bc 100644
--- a/board/siemens/draco/Kconfig
+++ b/board/siemens/draco/Kconfig
@@ -1,19 +1,3 @@
-if TARGET_DRACO
-
-config SYS_BOARD
-	default "draco"
-
-config SYS_VENDOR
-	default "siemens"
-
-config SYS_SOC
-	default "am33xx"
-
-config SYS_CONFIG_NAME
-	default "draco"
-
-endif
-
 if TARGET_THUBAN
 
 config SYS_BOARD
@@ -26,7 +10,7 @@
 	default "am33xx"
 
 config SYS_CONFIG_NAME
-	default "thuban"
+	default "draco-thuban"
 
 endif
 
@@ -42,7 +26,7 @@
 	default "am33xx"
 
 config SYS_CONFIG_NAME
-	default "rastaban"
+	default "draco-rastaban"
 
 endif
 
@@ -58,7 +42,7 @@
         default "am33xx"
 
 config SYS_CONFIG_NAME
-        default "etamin"
+        default "draco-etamin"
 
 config NAND_CS_INIT
 	def_bool y