settings_org: Fix incorrect selector for the save changes button.
settings_org: Fix incorrect selector for the save changes button.

This change fixes a bug where pressing Enter does not save the
changes as expected, due to an incorrect selector, when the
save/discard changes button shows up in settings. Tested by changing
the Organization name and pressing Enter at Manage Organization >
Organization profile > Organization name.

hackerkid/zulip,eeshangarg/zulip,punchagan/zulip,zulip/zulip,kou/zulip,zulip/zulip,rht/zulip,eeshangarg/zulip,punchagan/zulip,punchagan/zulip,punchagan/zulip,andersk/zulip,zulip/zulip,zulip/zulip,hackerkid/zulip,hackerkid/zulip,eeshangarg/zulip,rht/zulip,punchagan/zulip,andersk/zulip,rht/zulip,eeshangarg/zulip,rht/zulip,andersk/zulip,rht/zulip,zulip/zulip,zulip/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,kou/zulip,eeshangarg/zulip,rht/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,andersk/zulip,rht/zulip,punchagan/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,eeshangarg/zulip,kou/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,kou/zulip