microblaze: Wire-up getrandom syscall

Add new getrandom syscall.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

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

@@ -400,5 +400,6 @@
 #define __NR_sched_getattr	382
 #define __NR_renameat2		383
 #define __NR_seccomp		384
+#define __NR_getrandom		385
 
 #endif /* _UAPI_ASM_MICROBLAZE_UNISTD_H */

arch/microblaze/kernel/syscall_table.S

@@ -385,3 +385,4 @@ ENTRY(sys_call_table)
 	.long sys_sched_getattr
 	.long sys_renameat2
 	.long sys_seccomp
+	.long sys_getrandom		/* 385 */