CheckSizeArgForCreate checks that size is specified when snapshot
or source volume aren't. But when size is 0, CheckSizeArgForCreate
action works wrong and generates error: 'Size is a required
parameter if snapshot or source volume is not specified', meanwhile
user expected to see: 'Volume size '0' must be greater than 0'.
Change-Id: I164970a600d6e86bd7076dd485f676a703f5e487
Closes-Bug: #1454276