staging: mfd: hi6421-spmi-pmic: cleanup hi6421-spmi-pmic.h header

There are several external vars that are defined there, which
are not needed anymore.

Get rid of them.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/3dbc3f3876275404153da52b84e5dcef09faf644.1597647359.git.mchehab+huawei@kernel.org


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