spi: bcm2835: Call the dedicated transfer completion function.

spi_finalize_current_transfer currently only calls "complete", so no
functional change is expected.

Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Link: https://lore.kernel.org/r/633c3d5c350dde4d14ce2120c32698c25b95d302.1610062884.git.plr.vincent@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>