Simplify kallsyms_lookup()

Several kallsyms_lookup() pass dummy arguments but only need, say, module's
name.  Make kallsyms_lookup() accept NULLs where possible.

Also, makes picture clearer about what interfaces are needed for all symbol
resolving business.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/parisc/kernel/unwind.c b/arch/parisc/kernel/unwind.c
index 5f75b3e..89c0370 100644
--- a/arch/parisc/kernel/unwind.c
+++ b/arch/parisc/kernel/unwind.c
@@ -216,11 +216,8 @@
 		/* Handle some frequent special cases.... */
 		{
 			char symname[KSYM_NAME_LEN+1];
-			char *modname;
-			unsigned long symsize, offset;
 
-			kallsyms_lookup(info->ip, &symsize, &offset,
-					&modname, symname);
+			kallsyms_lookup(info->ip, NULL, NULL, NULL, symname);
 
 			dbg("info->ip = 0x%lx, name = %s\n", info->ip, symname);