arm: am335x-pdu001: Remove SPI support

On this board SPI is only used to configure the SoC driving the LC TFT
display which is not used in U-Boot. Hence remove SPI support.

Signed-off-by: Felix Brack <fb@ltec.ch>
diff --git a/configs/am335x_pdu001_defconfig b/configs/am335x_pdu001_defconfig
index e93c411..2a8d318 100644
--- a/configs/am335x_pdu001_defconfig
+++ b/configs/am335x_pdu001_defconfig
@@ -50,6 +50,5 @@
 CONFIG_DM_REGULATOR_FIXED=y
 CONFIG_DM_REGULATOR_TPS65910=y
 CONFIG_CONS_INDEX=4
-CONFIG_SPI=y
 # CONFIG_USE_TINY_PRINTF is not set
 # CONFIG_EFI_LOADER is not set