blackfin: Wire up missing syscalls

The related syscalls are below which may cause samples/kdbus building
break in next-20150401 tree, the related information and error:

CALL scripts/checksyscalls.sh
<stdin>:1223:2: warning: #warning syscall kcmp not implemented [-Wcpp]
<stdin>:1226:2: warning: #warning syscall finit_module not implemented [-Wcpp]
<stdin>:1229:2: warning: #warning syscall sched_setattr not implemented [-Wcpp]
<stdin>:1232:2: warning: #warning syscall sched_getattr not implemented [-Wcpp]
<stdin>:1235:2: warning: #warning syscall renameat2 not implemented [-Wcpp]
<stdin>:1238:2: warning: #warning syscall seccomp not implemented [-Wcpp]
<stdin>:1241:2: warning: #warning syscall getrandom not implemented [-Wcpp]
<stdin>:1244:2: warning: #warning syscall memfd_create not implemented [-Wcpp]
<stdin>:1247:2: warning: #warning syscall bpf not implemented [-Wcpp]
<stdin>:1250:2: warning: #warning syscall execveat not implemented [-Wcpp]
[...]
HOSTCC samples/kdbus/kdbus-workers
samples/kdbus/kdbus-workers.c: In function ‘prime_new’:
samples/kdbus/kdbus-workers.c:930:18: error: ‘__NR_memfd_create’ undeclared (first use in this function)
p->fd = syscall(__NR_memfd_create, "prime-area", MFD_CLOEXEC);
^
samples/kdbus/kdbus-workers.c:930:18: note: each undeclared identifier is reported only once for each function it appears in

Signed-off-by: Chen Gang <[e-mail]>

arch/blackfin/include/uapi/asm/unistd.h

···
 #define __NR_sendmmsg		380
 #define __NR_process_vm_readv	381
 #define __NR_process_vm_writev	382
+#define __NR_kcmp		383
+#define __NR_finit_module	384
+#define __NR_sched_setattr	385
+#define __NR_sched_getattr	386
+#define __NR_renameat2		387
+#define __NR_seccomp		388
+#define __NR_getrandom		389
+#define __NR_memfd_create	390
+#define __NR_bpf		391
+#define __NR_execveat		392
 
-#define __NR_syscall		383
+#define __NR_syscall		393  /* For internal using, not implemented */
 #define NR_syscalls		__NR_syscall
 
 /* Old optional stuff no one actually uses */

arch/blackfin/mach-common/entry.S

···
 	.long _sys_sendmmsg		/* 380 */
 	.long _sys_process_vm_readv
 	.long _sys_process_vm_writev
+	.long _sys_kcmp
+	.long _sys_finit_module
+	.long _sys_sched_setattr	/* 385 */
+	.long _sys_sched_getattr
+	.long _sys_renameat2
+	.long _sys_seccomp
+	.long _sys_getrandom
+	.long _sys_memfd_create		/* 390 */
+	.long _sys_bpf
+	.long _sys_execveat
 
 	.rept NR_syscalls-(.-_sys_call_table)/4
 	.long _sys_ni_syscall