MIPS: Loongson1B: improve ls1x_serial_setup()

Improve ls1x_serial_setup().

Signed-off-by: Kelvin Cheung <keguang.zhang@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/4432
Signed-off-by: John Crispin <blogic@openwrt.org>

arch/mips/include/asm/mach-loongson1/platform.h

@@ -19,6 +19,6 @@ extern struct platform_device ls1x_ehci_device;
 extern struct platform_device ls1x_rtc_device;
 
 extern void __init ls1x_clk_init(void);
-void ls1x_serial_setup(void);
+extern void __init ls1x_serial_setup(struct platform_device *pdev);
 
 #endif /* __ASM_MACH_LOONGSON1_PLATFORM_H */