media: i2c: st-mipid02: fix mipid02_stream_enable error handling

Following addition of cascaded s_stream call within
mipid02_stream_enable and mipid02_stream_disable,
the mipid02_stream_enable error handling must be fixed to simply
disable the clocks & data lanes without also calling
again the s_stream of the source subdev.

Moreover, main control registers are reset to 0 for all cases
of error within the mipid02_stream_enable even if they haven't yet
been written. Correct this behavior by simply returning an
error when register clear are not necessary.

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>