MIPS: Fix always CONFIG_LOONGSON_UART_BASE=y

Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org>
Cc: linux-mips <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/2055/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/loongson/Kconfig

+if MACH_LOONGSON
+
 choice
 	prompt "Machine Type"
-	depends on MACH_LOONGSON
 
 config LEMOTE_FULOONG2E
 	bool "Lemote Fuloong(2e) mini-PC"
@@ -87,3 +88,5 @@ config LOONGSON_UART_BASE
 config LOONGSON_MC146818
 	bool
 	default n
+
+endif # MACH_LOONGSON