ASoC: format_register_str: Don't clip register values

wordsize is used as the textual width of a register address.

regsize is used as the textual width of a register value.

The assignments to these values were swapped. In the case of WM8903, which
has 8-bit register addresses and 16-bit register values, this caused the
register values to be clipped to 2 digits instead of the full 4.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>