sunhme: Clean up debug infrastructure

Remove all the single-use debug conditionals, and just collect the debug
defines at the top of the file. HMD seems like it is used for general debug
info, so just redefine it as pr_debug. Additionally, instead of using the
default loglevel, use the debug loglevel for debugging.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>