ASoC: codecs: skip enabling codec power supplies when not defined

When codec power supplies are from external/battery source and enabled
by default, there's no need to enable these power supplies in probe
functions. When the codec power supplies is not defined in device tree,
avoid inititialzing, enabling and disabling it.

Change-Id: Iebb08cca163c966ae8cbe2d20db174fc5ddf03f1
Signed-off-by: Meng Wang <mengw@codeaurora.org>