staging: dwc2: unshift non-bool register value constants
Various register fields wider than one bit have constants defined for
their value. Previously, these registers would define the values as they
appear in the register, so shifted to the right to the position the
value appears in the register.
This commit changes those constants to their natural values (e.g, 0, 1,
2, etc.), as they are after shifting the register value to the right.
This also changes all relevant code to shift the values before comparing
them with constants.
This has the advantage that the values can be stored in smaller
variables (now they always require a u32) and makes the handling of
these values more consistent with other register fields that represent
natural numbers instead of enumerations (e.g., number of host channels).