lxd-setup-lvm-storage: Add default size of 10G
lxd-setup-lvm-storage: Add default size of 10G

-s is optional, but if you don't specify it, you just get errors.
A default size fixes this.

Signed-off-by: Michael McCracken <678f76d0129c6a47299e3c6abb92ed26d253a960@canonical.com>

hallyn/lxd,stgraber/lxd,akshaykarle/lxd,mjeanson/lxd,pcdummy/lxd,ollie314/lxd,techtonik/lxd,yura-pakhuchiy/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,ollie314/lxd,Skarlso/lxd,jsavikko/lxd,lxc/lxd,erikmack/lxd,pcdummy/lxd,lxc/lxd,stgraber/lxd,Skarlso/lxd,erikmack/lxd,yura-pakhuchiy/lxd,jsavikko/lxd,dustinkirkland/lxd,lxc/lxd,mjeanson/lxd,dustinkirkland/lxd,hallyn/lxd,georghopp/lxd,chrisglass/lxd,chrisglass/lxd,Skarlso/lxd,stgraber/lxd,akshaykarle/lxd,atxwebs/lxd,yura-pakhuchiy/lxd,Skarlso/lxd,atxwebs/lxd,hallyn/lxd,erikmack/lxd,techtonik/lxd,techtonik/lxd,stgraber/lxd,atxwebs/lxd,lxc/lxd,mjeanson/lxd,stgraber/lxd,ollie314/lxd,chrisglass/lxd,stgraber/lxd,lxc/lxd,dustinkirkland/lxd,atxwebs/lxd,georghopp/lxd,hallyn/lxd,georghopp/lxd,jsavikko/lxd,pcdummy/lxd,akshaykarle/lxd,stgraber/lxd,lxc/lxd