Convert CONFIG_SYS_SPD_BUS_NUM to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_SPD_BUS_NUM

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/P4080DS_SDCARD_defconfig b/configs/P4080DS_SDCARD_defconfig
index 867f8aa..e87d506 100644
--- a/configs/P4080DS_SDCARD_defconfig
+++ b/configs/P4080DS_SDCARD_defconfig
@@ -47,6 +47,7 @@
 CONFIG_DM=y
 CONFIG_LBA48=y
 CONFIG_FSL_CAAM=y
+CONFIG_SYS_SPD_BUS_NUM=1
 CONFIG_DDR_ECC=y
 CONFIG_ECC_INIT_VIA_DDRCONTROLLER=y
 CONFIG_SYS_BR0_PRELIM_BOOL=y