omap4: duovero: Disable EFI booting

The DuoVero board fails to compile with EFI enabled as the generated
binaries are too large.  As this platform doesn't currently need EFI,
disable this feature.

Signed-off-by: Ash Charles <ashcharles@gmail.com>
diff --git a/include/configs/duovero.h b/include/configs/duovero.h
index d8f48ef..98afe27 100644
--- a/include/configs/duovero.h
+++ b/include/configs/duovero.h
@@ -22,6 +22,7 @@
 #include <configs/ti_omap4_common.h>
 
 #undef CONFIG_SPL_OS_BOOT
+#undef CONFIG_EFI_PARTITION
 
 #undef CONFIG_SYS_EMIF_PRECALCULATED_TIMING_REGS
 #define CONFIG_SYS_AUTOMATIC_SDRAM_DETECTION