FSL: Convert board/freescale/common/Makefile to use CONFIG_

Convert the board/freescale/common/Makefile to use
CONFIG_* options to select which files to conditionally
compile into the board/freescale/common library rather
than conditionally compiling entire files.

Now handles::
    CONFIG_FSL_PIXIS
    CONFIG_FSL_DIU_FB
    CONFIG_PQ_MDS_PIB

CONFIG_ID_EEPROM is introduced until CFG_ID_EEPROM is gone.

Signed-off-by: Jon Loeliger <jdl@freescale.com>
diff --git a/include/configs/MPC8641HPCN.h b/include/configs/MPC8641HPCN.h
index 7f485c6..ab875f0 100644
--- a/include/configs/MPC8641HPCN.h
+++ b/include/configs/MPC8641HPCN.h
@@ -152,6 +152,9 @@
 #endif
 
 #define CFG_ID_EEPROM	1
+#ifdef CFG_ID_EEPROM
+#define CONFIG_ID_EEPROM
+#endif
 #define ID_EEPROM_ADDR 0x57
 
 /*