sunxi: Add support for UART0 in PB pin group on A83T

On A83T, PB9,PB10 are UART0 pins.
On allwinner A83T Dev board(h8homlet), this uart0 serial connector
is exposed.

Signed-off-by: Vishnu Patekar <vishnupatekar0510@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>