submodule--helper: drop "update --prefix <pfx>" for "-C <pfx> update"

Since 29a5e9e (submodule--helper update-clone: learn --init,
2022-03-04) we've been passing "-C <prefix>" from "git-submodule.sh"
whenever we pass "--prefix <prefix>", so the latter is redundant to
the former. Let's drop the "--prefix" option.

Suggested-by: Glen Choo <[email protected]>
Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>

Author: avar

builtin/submodule--helper.c

@@ -2643,9 +2643,6 @@ static int module_update(int argc, const char **argv, const char *prefix)
 			 N_("traverse submodules recursively")),
 		OPT_BOOL('N', "no-fetch", &opt.nofetch,
 			 N_("don't fetch new objects from the remote site")),
-		OPT_STRING(0, "prefix", &opt.prefix,
-			   N_("path"),
-			   N_("path into the working tree")),
 		OPT_SET_INT(0, "checkout", &opt.update_default,
 			N_("use the 'checkout' update strategy (default)"),
 			SM_UPDATE_CHECKOUT),
@@ -2701,6 +2698,7 @@ static int module_update(int argc, const char **argv, const char *prefix)
 	}
 
 	opt.filter_options = &filter_options;
+	opt.prefix = prefix;
 
 	if (opt.update_default)
 		opt.update_strategy.type = opt.update_default;

git-submodule.sh

@@ -343,7 +343,6 @@ cmd_update()
 		${recursive:+--recursive} \
 		${init:+--init} \
 		${nofetch:+--no-fetch} \
-		${wt_prefix:+--prefix "$wt_prefix"} \
 		${rebase:+--rebase} \
 		${merge:+--merge} \
 		${checkout:+--checkout} \