MIPS: replace open-coded init_dsp

There is already an init_dsp function which checks cpu_has_dsp & calls
__init_dsp if it does. Make use of it instead of duplicating the same
code.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Qais Yousef <qais.yousef@imgtec.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6148/

arch/mips/kernel/process.c

@@ -64,8 +64,7 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 	regs->cp0_status = status;
 	clear_used_math();
 	clear_fpu_owner();
-	if (cpu_has_dsp)
-		__init_dsp();
+	init_dsp();
 	regs->cp0_epc = pc;
 	regs->regs[29] = sp;
 }