kvm tools: Make code mostly checkpatch clean

kvm tools: Make code mostly checkpatch clean

This patch fixes code style issues pointed out by scripts/checkpatch. However,
some reported errors are false positives. In particular, the warning:

  WARNING: line over 80 characters

is too strict for our code and thus needs to action to be taken.

Signed-off-by: Pekka Enberg <penberg@kernel.org>