net: ipa: switch to version based configuration

Rename the SDM845 configuration data file so that its name is
derived from its IPA version.  I am not aware of any special IPA
behavior or handling that would be based on a specific SoC (as
opposed to a specific version of the IPA it contains).

Update a few other references to the code that talk about the SDM845
rather than just IPA v3.5.1.

Signed-off-by: Alex Elder <elder@linaro.org>