remote.c: specify correct plural form in "commit diverge" message

We need to count both "ours" and "theirs" commits when selecting plural
form for this message. Note that even though in this block, both ours
and theirs must be positive (i.e. can't be in singular form), we still
keep Q_(singular, plural) because languages other than English may have
more than one plural form.
Reported-by: NAlfonsogonzalez, Ernesto (GE Digital) <ernesto.alfonsogonzalez@ge.com>
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

remote.c

@@ -2156,7 +2156,7 @@ int format_tracking_info(struct branch *branch, struct strbuf *sb)
 			   "Your branch and '%s' have diverged,\n"
 			       "and have %d and %d different commits each, "
 			       "respectively.\n",
-			   theirs),
+			   ours + theirs),
 			base, ours, theirs);
 		if (advice_status_hints)
 			strbuf_addf(sb,