IRQ modification is part of device emulation and should be done while
the BQL is held to prevent races when MTTCG is enabled. This adds
assertions in the hw emulation layer and wraps the calls from helpers
in the BQL.
Reported-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>