x86: Don't set up MTRRs if previously done

When starting U-Boot from a previous-stage bootloader we presumably don't
need to set up the variable MTRRs. In fact this could be harmful if the
existing settings are not what U-Boot uses.

Skip that step in this case.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

arch/x86/cpu/i386/cpu.c

@@ -423,7 +423,7 @@ static void setup_mtrr(void)
 	u64 mtrr_cap;
 
 	/* Configure fixed range MTRRs for some legacy regions */
-	if (!gd->arch.has_mtrr)
+	if (!gd->arch.has_mtrr || !ll_boot_init())
 		return;
 
 	mtrr_cap = native_read_msr(MTRR_CAP_MSR);