configs: mx6sabresd: Reduce SPL size by disabling DOS, EXT and EFI support

With DM and FIT enabled in SPL, there is an sram overflow. By disabling
CONFIG_SPL_DOS_PARTITION, CONFIG_SPL_EXT_SUPPORT and
CONFIG_SPL_EFI_PARTITION, we get to keep the 'one binary to fit all'
for imx6[q|qp|dl] on sabresd since the final SPL image is now under 64KB.

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
diff --git a/configs/mx6sabresd_defconfig b/configs/mx6sabresd_defconfig
index 80c01f2..bd2d4ee 100644
--- a/configs/mx6sabresd_defconfig
+++ b/configs/mx6sabresd_defconfig
@@ -53,6 +53,8 @@
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
 CONFIG_EFI_PARTITION=y
+# CONFIG_SPL_DOS_PARTITION is not set
+# CONFIG_SPL_EFI_PARTITION is not set
 CONFIG_OF_CONTROL=y
 CONFIG_SPL_OF_CONTROL=y
 CONFIG_DEFAULT_DEVICE_TREE="imx6q-sabresd"