staging: omap-thermal: remove TODO entry suggesting regmap usage

It is hard to use regmap because benefit of using regmap cache
may not be applicable as there is a specific sequence to
restore the bandgap context.

Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/omap-thermal/TODO

@@ -1,7 +1,6 @@
 List of TODOs (by Eduardo Valentin)
 
 on omap-bandgap.c:
-- Improve driver code by adding usage of regmap-mmio
 - Test every exposed API to userland
 - Add support to hwmon
 - Review and revisit all API exposed