Any SoC which supports the einput, odrain, lock, ioreset, or rcv_sel
options has the relevant HW register fields in the same register as the
mux function selection. Similarly, the drvtype option is always in the
drive register, if it is supported at all. Hence, we don't need to have
struct *_reg fields in the pin group table to define which register and
bank to use for those options. Delete this to save space in the driver's
data tables.

However, many of those options are not supported on all SoCs, or not
supported on some pingroups. We need a way to detect when they are
supported. Previously, this was indicated by setting the struct *_reg
field to -1. With the struct *_reg fields removed, we use the struct
*_bit fields for this purpose instead. The struct *_bit fields need to
be expanded from 5 to 6 bits in order to store a value outside the valid
HW bit range of 0..31.

Even without removing the struct *_reg fields, we still need to add code
to validate the struct *_bit fields, since some struct *_bit fields were
already being set to -1, without an option-specific struct *_reg field to
"guard" them. In other words, before this change, the pinmux driver might
allow some unsupported options to be written to HW.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>