lib/cpio: Make find_cpio_data()'s offset arg optional

Some callers don't use it so make it optional.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1465225850-7352-4-git-send-email-bp@alien8.deSigned-off-by: Ingo Molnar <mingo@kernel.org>

lib/earlycpio.c

@@ -125,7 +125,10 @@ struct cpio_data find_cpio_data(const char *path, void *data,
 		if ((ch[C_MODE] & 0170000) == 0100000 &&
 		    ch[C_NAMESIZE] >= mypathsize &&
 		    !memcmp(p, path, mypathsize)) {
+
+			if (nextoff)
 				*nextoff = (long)nptr - (long)data;
+
 			if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
 				pr_warn(
 				"File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",