hwmon: (dell-smm) Pack the whole smm_regs struct

When desiring the whole struct to be packed, __packed
should be applied to the whole struct, not just
every struct member except the first one.

Tested on a Dell Inspiron 3505.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20211221162805.104202-1-W_Armin@gmx.de


Signed-off-by: Guenter Roeck <linux@roeck-us.net>