[MIPS] Pb1200/DBAu1200 code style cleanup

Fix several errors and warnings given by checkpatch.pl:

- use of C99 // comments;

- initialization of a 'static' variable to 0;

- space after opening and before closing parentheses;

- missing space between 'for' and opening parenthesis;

- macros with complex values not enclosed in parentheses;

- printk() without KERN_* facility level;

- unnecessary braces for single-statement block;

- using simple_strtol() where strict_strtol() could be used;

- line over 80 characters.

In addition to these changes, also do the following:

- mention DBAu1200 board in the Makefile;

- replace the group of #include/#ifdef directives by a single
  #include <au1xxx.h> since this header contains the needed stuff;

- properly indent the blocks;

- insert spaces between operator and its operands, remove excess spaces
  there;

- remove needless parentheses and add some for clarity;

- replace numeric literals/expressions with the matching macros;

- remove space after the type c...