target/mips: Fix the title of translate.c

Replace MIPS32 with MIPS, since the file covers all generations
of MIPS architectures.
Reviewed-by: NStefan Markovic <smarkovic@wavecomp.com>
Signed-off-by: NAleksandar Markovic <amarkovic@wavecomp.com>

target/mips/translate.c

 /*
- *  MIPS32 emulation for qemu: main translation routines.
+ *  MIPS emulation for QEMU - main translation routines
  *
  *  Copyright (c) 2004-2005 Jocelyn Mayer
  *  Copyright (c) 2006 Marius Groeger (FPU operations)