os.linux: make SoftIrqs support being raised while executing.

os.linux: make SoftIrqs support being raised while executing.

In order to do this, statevalues are now bitmasks. Many more checks
at SoftIrq Raise, Entry and Exit handlers now take into account if
there are other SoftIrqs running and will retain their state.

Fixes part 2 of bug 381497

Change-Id: I2f109d1e4e3a227c10dcdf8f54df7b42c7776d4a
Signed-off-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/66259
Reviewed-by: Alexandre Montplaisir <alexmonthy@efficios.com>
Tested-by: Alexandre Montplaisir <alexmonthy@efficios.com>