doc: added comment for hack.

Signed-off-by: ridale <[email protected]>

Author: ridale

libethdrivers/src/plat/imx6/uboot/imx-regs.h

@@ -32,7 +32,7 @@
 
 #define ROMCP_ARB_BASE_ADDR             0x00000000
 #define ROMCP_ARB_END_ADDR              0x000FFFFF
-
+// HACK use imx6 register layout for imx8
 #if defined (CONFIG_PLAT_IMX8MQ_EVK)
     #define CONFIG_PLAT_IMX6DQ
 #endif