add kernel-cmdline support for interrupt threads priorities

Hello Steven,

Back in August we all had a discussion about the default priorities of IRQ-threads and softirqs, and the lack of a mechanism to configure them from within the kernel.
(see http://www.mail-archive.com/[email protected]/msg01022.html)

Here is a patchset that implements such a nice feature from the kernel cmdline, similar to what we all agreed on, back then.

The set exist of 3 parts:
1) add a generic routine to the kernel commandline-parse-library to parse the format of the map as we agreed on.
2) Add a __setup(irq_pmap=) routine to kernel/irq/manage.c
3) Add a __setup(sirq_pmap=) routine to kernel/softirq.c

I hope you can find the time to review this set.

Kind Regards,

Remy Bohmer