Revert "rainier and tacoma: Build u-boot spl"

This reverts commit f2f334e6221b659934a8e72f5ca1aa8c9b8ae173.

The u-boot openbmc spl defconfig is still in review:
https://patchwork.ozlabs.org/project/openbmc/patch/1586370073-71433-1-git-send-email-anoo@linux.ibm.com/

Change-Id: I58b1da70d8b970ced51ef0d84673ffa42e5422c4
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/meta-witherspoon/conf/machine/witherspoon-tacoma.conf b/meta-witherspoon/conf/machine/witherspoon-tacoma.conf
index c367e4c..4d94d9e 100644
--- a/meta-witherspoon/conf/machine/witherspoon-tacoma.conf
+++ b/meta-witherspoon/conf/machine/witherspoon-tacoma.conf
@@ -1,7 +1,6 @@
 KERNEL_DEVICETREE = "aspeed-bmc-opp-tacoma.dtb"
-UBOOT_MACHINE = "ast2600_openbmc_spl_defconfig"
+UBOOT_MACHINE = "ast2600_openbmc_defconfig"
 UBOOT_DEVICETREE = "ast2600-tacoma"
-SPL_BINARY = "spl/u-boot-spl.bin"
 
 IMAGE_FSTYPES += "ext4 mmc-ext4-tar"