xpl: Rename spl_phase() to xpl_phase()

Rename this function to indicate that it refers to any xPL phase.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/intel_common/mrc.c b/arch/x86/cpu/intel_common/mrc.c
index c834c05..baa1f0e 100644
--- a/arch/x86/cpu/intel_common/mrc.c
+++ b/arch/x86/cpu/intel_common/mrc.c
@@ -259,7 +259,7 @@
 		return ret;
 
 	delay = dev_read_u32_default(dev, "fspm,training-delay", 0);
-	if (spl_phase() == PHASE_SPL) {
+	if (xpl_phase() == PHASE_SPL) {
 		if (delay)
 			printf("SDRAM training (%d seconds)...", delay);
 		else