pinctrl: uniphier: remove wrong pin-mux functions for ProXstream2

These are pin group names, not function names.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

drivers/pinctrl/uniphier/pinctrl-uniphier-pxs2.c

@@ -96,11 +96,9 @@ static const char * const uniphier_pxs2_functions[] = {
 	"nand",
 	"sd",
 	"uart0",
-	"uart0b",
 	"uart1",
 	"uart2",
 	"uart3",
-	"uart3b",
 	"usb0",
 	"usb1",
 	"usb2",