x86: Don't try to boot Linux from SPL

Booting into linux from 64-bit U-Boot is not yet supported. Avoid bringing
in the bootm code until it is implemented.

Of course 32-bit U-Boot still supports booting into both 32- and 64-bit
kernels.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 05e212f..1c2c085 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -10,7 +10,9 @@
 obj-y += bios_asm.o
 obj-y += bios_interrupts.o
 endif
+ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_CMD_BOOTM) += bootm.o
+endif
 obj-y	+= cmd_boot.o
 obj-$(CONFIG_SEABIOS) += coreboot_table.o
 obj-$(CONFIG_EFI) += efi/
@@ -37,7 +39,9 @@
 obj-$(CONFIG_GENERATE_ACPI_TABLE) += acpi_table.o
 endif
 obj-y	+= tables.o
+ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_CMD_ZBOOT)	+= zimage.o
+endif
 obj-$(CONFIG_HAVE_FSP) += fsp/
 obj-$(CONFIG_SPL_BUILD) += spl.o