[FIX] jQuery.sap.initMobile: Check for existence of homeIcon property

initMobile used homeIcon property of its options argument even if
options was not set, which lead to an error. Now it checks for the
existence of the options-object first.

Change-Id: Icae5684f232d99b7e727791bde412325e200bb95
Merge "[FIX] jQuery.sap.initMobile: Check for existence of homeIcon property"