sandbox: Enable dhry command

Provide access to the dhrystone benchmark command.
Signed-off-by: NSimon Glass <sjg@chromium.org>

configs/sandbox_defconfig

@@ -18,6 +18,7 @@ CONFIG_PCI_SANDBOX=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_SANDBOX=y
 CONFIG_CMD_CROS_EC=y
+CONFIG_CMD_DHRYSTONE=y
 CONFIG_CROS_EC=y
 CONFIG_CROS_EC_SANDBOX=y
 CONFIG_DM_ETH=y