luci-mod-network: fix device dependencies in add interface dialog

Commit b7f3cf66 "luci-mod-network: drop support for *adding* legacy bridges"
dropped the protocol dependcies of the ifname/device selector in the add new
interface dialog.

Re-add the required dependencies and swap the order of the protocol and
device inputs while we're at it since latter depends on the former.

Fixes: b7f3cf66

 ("luci-mod-network: drop support for *adding* legacy bridges")
Signed-off-by: Jo-Philipp Wich <jo@mein.io>