mshv: Fix level-triggered check on uninitialized data

mshv: Fix level-triggered check on uninitialized data

In mshv_irqfd_assign(), the level-triggered validation for resample
irqfds checks irqfd_lapic_irq.lapic_control.level_triggered before
mshv_irqfd_update() has populated the field. Since the irqfd struct is
zero-allocated, level_triggered is always 0 at that point, causing the
check to always reject resample irqfds with -EINVAL. This makes
level-triggered interrupt resampling — used to avoid interrupt storms
with assigned devices — completely non-functional.

Move the check after the mshv_irqfd_update() call, which resolves the
IRQ routing entry and populates irqfd_lapic_irq with the actual trigger
mode.

Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs")
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>