configs: net: dm9000: Move new Kconfig option to board configs

Drop legacy #define CONFIG_DRIVER_DM9000 from board include/configs/
and enable the same in Kconfig configs/ .

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/configs/M5253DEMO_defconfig b/configs/M5253DEMO_defconfig
index d5a02cd..0d298e3 100644
--- a/configs/M5253DEMO_defconfig
+++ b/configs/M5253DEMO_defconfig
@@ -37,4 +37,5 @@
 CONFIG_SYS_I2C_SPEED=80000
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_USE_SYS_MAX_FLASH_BANKS=y
+CONFIG_DRIVER_DM9000=y
 CONFIG_MCFUART=y