Doc: Fix apidoc for QQuickLoader::sourceComponent
Doc: Fix apidoc for QQuickLoader::sourceComponent

Setting this to an empty string doesn't make sense nor works

Change-Id: I4dd89d0356da30bc46e5fdac827e30b6f9a6a7a4
Reviewed-by: J-P Nurmi <b84a892f57a298bb5dae653b4e188948a84d5549@digia.com>
Reviewed-by: Gunnar Sletta <d0b71651f3efaa9fda200bbcc395b7b82a871fdd@jollamobile.com>
Reviewed-by: Topi Reiniö <92400b03a70fe3119347f89b476f73d34ae93598@digia.com>
Reviewed-by: Alan Alpert <da25f2afbbb946022229108d81aeba0c6b35c5c3@blackberry.com>

qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative