This patch splits pin bank description into two structures, one
describing bank type (currently only bitfield widths), which can be
shared across multiple banks and second containing bank-specific
parameters including a pointer to a bank type struct.

It is a prerequisite for further patch removing the statically hardcoded
register offsets, making it impossible to support SoCs with different
set and order of pin control registers.
Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>