efl_ui/scroller: directly trigger group_calc if pan is resized during canvas calc

efl_ui/scroller: directly trigger group_calc if pan is resized during canvas calc

this is the time when all calculations need to be handled, so ensure that the
widget directly updates itself here instead of deferring in order to avoid
infinite recalc loops

Reviewed-by: Marcel Hollerbach <mail@marcel-hollerbach.de>
Differential Revision: https://phab.enlightenment.org/D9592