sandbox: Use defconfig to enable features

Stop using the sandbox arch Kconfig to override defaults for config
options. This is a bit of abuse and may be causing build problems.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

arch/sandbox/Kconfig

@@ -10,9 +10,6 @@ config SYS_BOARD
 config SYS_CONFIG_NAME
 	default "sandbox"
 
-config DM_TEST
-	default y
-
 config PCI
 	bool "PCI support"
 	help
@@ -20,16 +17,4 @@ config PCI
 	  used on some devices to allow the CPU to communicate with its
 	  peripherals.
 
-config NET
-	default y
-
-config NETDEVICES
-	default y
-
-config DM_ETH
-	default y
-
-config ETH_SANDBOX_RAW
-	default y
-
 endmenu

configs/sandbox_defconfig

@@ -1,4 +1,7 @@
 CONFIG_DM_USB=y
+CONFIG_NET=y
+CONFIG_NETDEVICES=y
+CONFIG_DM_ETH=y
 CONFIG_PCI=y
 CONFIG_SYS_VSNPRINTF=y
 CONFIG_DEFAULT_DEVICE_TREE="sandbox"
@@ -35,3 +38,4 @@ CONFIG_USB_STORAGE=y
 CONFIG_DM_RTC=y
 CONFIG_ERRNO_STR=y
 CONFIG_CMD_UT_TIME=y
+CONFIG_DM_TEST=y