blackfin: Remove exec_domain usage

As execution domain support is gone we can remove
signal translation from the signal code and remove
exec_domain from thread_info.

Signed-off-by: Richard Weinberger <richard@nod.at>

arch/blackfin/include/asm/thread_info.h

@@ -37,7 +37,6 @@ typedef unsigned long mm_segment_t;
 
 struct thread_info {
 	struct task_struct *task;	/* main task structure */
-	struct exec_domain *exec_domain;	/* execution domain */
 	unsigned long flags;	/* low level flags */
 	int cpu;		/* cpu we're on */
 	int preempt_count;	/* 0 => preemptable, <0 => BUG */
@@ -53,7 +52,6 @@ struct thread_info {
 #define INIT_THREAD_INFO(tsk)			\
 {						\
 	.task		= &tsk,			\
-	.exec_domain	= &default_exec_domain,	\
 	.flags		= 0,			\
 	.cpu		= 0,			\
 	.preempt_count	= INIT_PREEMPT_COUNT,	\