hwmon: Don't overuse I2C_CLIENT_MODULE_PARM

I2C_CLIENT_MODULE_PARM is overkill for force_subclients. We really
only use 4 out of the 48 slots, so we're better defining a custom
variable instead. This change saves 92 bytes of data for each of the
five drivers affected.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Acked-by: Marc Hulsman <m.hulsman@tudelft.nl>
Cc: Mark M. Hoffman <mhoffman@lightlink.com>