A F-9 KVM guest using virtio drivers currently fails to mount /boot during
rc.sysinit with this:

avc:  denied  { read } for pid=1081 comm="mount" name="vda1" dev=tmpfs ino=261
scontext=system_u:system_r:mount_t:s0 tcontext=system_u:object_r:device_t:s0
tclass=blk_file
avc:  denied  { getattr } for pid=1081 comm="mount" path="/dev/vda1" dev=tmpfs
ino=261 scontext=system_u:system_r:mount_t:s0
tcontext=system_u:object_r:device_t:s0 tclass=blk_file

Turns out to simply be that we need to set the file contexts on /dev/vda*
correctly. Patch below.

Adding to F9Blocker because if mounting /boot fails and the user tries to update
the kernel, things are going to get mightily screwed up.