umip: unblacklist and disable parallel make

The SRC_URI is up again, no need to blacklist the recipe if we disable parallel make

The following error can ocurr in a race condition:

scan.l:38:18: fatal error: gram.h: No such file or directory
http://errors.yoctoproject.org/Errors/Details/56158/



That is, the scan.l file is parsed before the gram.h file is generated.
To avoid this, we clear the PARALLEL_MAKE variable.

Signed-off-by: Adrian Dudau <adrian.dudau@enea.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>