gpio: ts5500: Fix Links to Technologic Systems web resources

Technologic Systems has rebranded as embeddedTS with the current
domain eventually going offline. Update web/doc URLs to correct
resource locations.

Signed-off-by: Kris Bahnsen <kris@embeddedTS.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>