platformPrefixIcon: Return given input if criteria not met
platformPrefixIcon: Return given input if criteria not met

If the given icon name is already available and cannot be prefixed by
platform because it does not exist, return early. (See: ionic, which
has logo-ionic.)

Signed-off-by: Kristofer Rye <1ed31cfd0b53bc3d1689a6fee6dbfc9507dffd22@gmail.com>
Tested-by: Kristofer Rye <1ed31cfd0b53bc3d1689a6fee6dbfc9507dffd22@gmail.com>

StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native