The pdata pointer is now always valid. Remove any conditions that check
its validity.

This patch is mostly just removing an indentation level. One variable had
to be moved due to the removal of a scope, and one comment was split into
two. Viewing the patch with git show/diff -b will show that it's actually
very small.

Note that WM8903_MIC_BIAS_CONTROL_0 is now written unconditionally,
whereas it used to be written only if pdata was supplied. Since
defpdata.micdet_cfg = 0, this unconditional write simply echos the HW
defaults in the case where pdata is not supplied.

Based on work by John Bonesio, but significantly reworked since then.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>