sandbox: Add and build AXI bus and device

Add test AXI drivers to the sandbox.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index afc3429..c8bd154 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -45,6 +45,7 @@
 CONFIG_CMD_SF=y
 CONFIG_CMD_SPI=y
 CONFIG_CMD_USB=y
+CONFIG_CMD_AXI=y
 CONFIG_CMD_TFTPPUT=y
 CONFIG_CMD_TFTPSRV=y
 CONFIG_CMD_RARP=y
@@ -80,6 +81,8 @@
 CONFIG_DEBUG_DEVRES=y
 CONFIG_ADC=y
 CONFIG_ADC_SANDBOX=y
+CONFIG_AXI=y
+CONFIG_AXI_SANDBOX=y
 CONFIG_CLK=y
 CONFIG_CPU=y
 CONFIG_DM_DEMO=y