mfd: wm5102: Don't wait for boot when boot sequencer is disabled

As we are using a custom boot sequence we don't need to wait for the
standard boot sequence in device init when the normal write sequence is
disabled.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>