global: Move remaining CONFIG_SYS_NS16550_* to CFG_SYS_NS16550_*

The rest of the unmigrated CONFIG symbols in the CONFIG_SYS_NS16550
namespace do not easily transition to Kconfig. In many cases they likely
should come from the device tree instead. Move these out of CONFIG
namespace and in to CFG namespace.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/armv8/fsl-layerscape/fdt.c b/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
index ee73457..4f91db4 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
+++ b/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
@@ -646,7 +646,7 @@
 
 #ifdef CONFIG_SYS_NS16550
 	do_fixup_by_compat_u32(blob, "fsl,ns16550",
-			       "clock-frequency", CONFIG_SYS_NS16550_CLK, 1);
+			       "clock-frequency", CFG_SYS_NS16550_CLK, 1);
 #endif
 
 	do_fixup_by_path_u32(blob, "/sysclk", "clock-frequency",