Input: snvs_pwrkey - fix SNVS_HPVIDR1 register address

Both i.MX6 and i.MX8 reference manuals list 0xBF8 as SNVS_HPVIDR1
(chapters 57.9 and 6.4.5 respectively).

Without this, trying to read the revision number results in 0 on
all revisions, causing the i.MX6 quirk to apply on all platforms,
which in turn causes the driver to synthesise power button release
events instead of passing the real one as they happen even on
platforms like i.MX8 where that's not wanted.

Fixes: 1a26c920

 ("Input: snvs_pwrkey - send key events for i.MX6 S, DL and Q")
Tested-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/4599101.ElGaqSPkdT@pliszka
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>