efi: Use the installed SMBIOS tables

U-Boot should set up the SMBIOS tables during startup, as it does on x86.
Ensure that it does this correctly on non-x86 machines too, by creating
an event spy for last-stage init.

Tidy up the installation-condition code while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/lib/Kconfig b/lib/Kconfig
index 6b5389f..79cf9ef 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -1049,6 +1049,7 @@
 	bool "SMBIOS support"
 	depends on X86 || EFI_LOADER
 	default y
+	select LAST_STAGE_INIT
 	help
 	  Indicates that this platform can support System Management BIOS
 	  (SMBIOS) tables. These provide various pieces of information about