staging: hi6421-spmi-pmic: rename spmi_device struct

Let's not call a pointer to spmi_device as pdev, as it is
something else.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/758e98d7f59d739b68b33723a02aca8b9464f8da.1626515862.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>