hwmon: (lm75) cleanup/reorg

Minor cleanup and reorg of the lm75 code.

 - Kconfig provides a larger list of lm75-compatible chips

 - A top comment now says what the driver does (!) ... as in, just
   what sort of sensor is this??

 - Section comments now delineate the various sections of the driver:
   hwmon attributes, driver binding, register access, module glue.
   One driver binding function moved out of the attribute section,
   as did the driver struct itself.

 - Minor tweaks to legacy probe logic:  correct a comment, and
   remove a pointless variable.

 - Whitespace, linelength, and comment fixes.

This patch should include no functional changes.  It's preparation
for adding new-style (driver model) I2C driver binding.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>