MIPS: Loongson: clean up the coding style

With the help of script/checkpatch.pl, i have cleaned up the coding
style.

1. remove un-needed header files and tune some comments.
2. remove some un-needed { }

add a new header file loongson.h:

3. move some common header files to loongson.h
4. move some common extern declartions to loongson.h

and this new header file is needed for future loongson2f support.

Signed-off-by: Wu Zhangjin <wuzj@lemote.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/lemote/lm2e/early_printk.c b/arch/mips/lemote/lm2e/early_printk.c
index 811c7de..3e0a6ea 100644
--- a/arch/mips/lemote/lm2e/early_printk.c
+++ b/arch/mips/lemote/lm2e/early_printk.c
@@ -9,11 +9,9 @@
  *  Free Software Foundation;  either version 2 of the  License, or (at your
  *  option) any later version.
  */
-#include <linux/io.h>
-#include <linux/init.h>
 #include <linux/serial_reg.h>
 
-#include <asm/mips-boards/bonito64.h>
+#include <loongson.h>
 
 #define UART_BASE (BONITO_PCIIO_BASE + 0x3f8)