KVM: Missing blank line after declarations in kvm_main.c

There are many Warnings like this:
WARNING: Missing a blank line after declarations
+	struct kvm_coalesced_mmio_zone zone;
+	r = -EFAULT;

This patch fixes these warnings to reduce noise when checking new
patches in kvm_main.c.

Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>