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/init.c b/arch/mips/lemote/lm2e/init.c
index 6fe624d..3abe927 100644
--- a/arch/mips/lemote/lm2e/init.c
+++ b/arch/mips/lemote/lm2e/init.c
@@ -8,15 +8,11 @@
  * option) any later version.
  */
 
-#include <linux/init.h>
 #include <linux/bootmem.h>
 
 #include <asm/bootinfo.h>
-#include <asm/mips-boards/bonito64.h>
 
-extern void __init prom_init_cmdline(void);
-extern void __init prom_init_env(void);
-extern void __init prom_init_memory(void);
+#include <loongson.h>
 
 void __init prom_init(void)
 {