pinctrl: sunxi: fix irq bank map for the Allwinner A100 pin controller

A100's pin starts with PB, so it should start with 1.

Fixes: 473436e7

 ("pinctrl: sunxi: add support for the Allwinner A100 pin controller")
Signed-off-by: Yangtao Li <frank@allwinnertech.com>
Link: https://lore.kernel.org/r/9db51667bf9065be55beafd56e5c319e3bbe8310.1604988979.git.frank@allwinnertech.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>