drivers: thermal: tsens: Merge tsens-common.c into tsens.c

tsens-common.c has outlived its usefuless. It was created expecting lots
of custom routines per version of the TSENS IP. We haven't needed those,
there is now only data in the version-specific files.

Merge the code for tsens-common.c into tsens.c. As a result,
- Remove any unnecessary forward declarations in tsens.h.
- Add a Linaro copyright to tsens.c.
- Fixup the Makefile to remove tsens-common.c.
- Where it made sense, fix some 80-column alignments in the
  tsens-common.c code being copied over.

There is no functional change with this patch.

Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/e30e2ba6fa5c007983afd4d7d4e0311c0b57917a.1588183879.git.amit.kucheria@linaro.org