icecc: Reduce verbosity with empty PARALLEL_MAKE

icecc: Reduce verbosity with empty PARALLEL_MAKE

Currently the icecc class prints a note for every package which
disables parallel make at parse time. This is unneccessary as many
packages don't support parallel building. Changing the log level from
info to debug hides these messages in normal builds without removing
the information when needed.

(From OE-Core rev: 6d2735629c20560a9406964195726b1a6e2d7d99)

Signed-off-by: Tobias Henkel <tobias.henkel@bmw-carit.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>