global: Move remaining CONFIG_SYS_* to CFG_SYS_*

The rest of the unmigrated CONFIG symbols in the CONFIG_SYS 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/drivers/clk/at91/compat.c b/drivers/clk/at91/compat.c
index b2bfb52..2fdc2fb 100644
--- a/drivers/clk/at91/compat.c
+++ b/drivers/clk/at91/compat.c
@@ -150,7 +150,7 @@
 
 static ulong at91_slow_clk_get_rate(struct clk *clk)
 {
-	return CONFIG_SYS_AT91_SLOW_CLOCK;
+	return CFG_SYS_AT91_SLOW_CLOCK;
 }
 
 static struct clk_ops at91_slow_clk_ops = {