Safari uses the first phone number listed in your Address Book card. There is no direction UI manipulation gesture for controlling this order, but there is a preference.
Address Book -> Preferences -> Template
Make the number type you wish to be used by Safari (Home, Work, etc) be the first number type in the template. Set others as needed.
By default, Address Book only has Work and Mobile on the template, so Safari will always choose Mobile over Home. If you make the first entry in the template “Home” and then add a new entry for “Mobile,” your home number will always be used for Safari Autofill.