drm/amd/display: Combine dce80 and dce100 i2c hw functions

[Why]
There are two versions of the hw function pointers: one for dce80
and one for all other versions.  These paired functions are
nearly identical.  dce80 and dce100 should not require
different i2c access functions.

[How]
Combine each pair of functions into a single function.  Mostly
the new functions are based on the dce100 versions as those
versions are newer, support more features, and
were more maintained.

Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Sun peng Li <Sunpeng.Li@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>