webdav: Do not return reference here.

This was missing in e07cefb4f7ba39d59d25815e208ed61269079142.

(cherry picked from commit 89df4412dcff84eb7ef77bf77b5db499ed44fb18)

Conflicts:
	ucb/source/ucp/webdav/webdavcontent.cxx

Change-Id: I1c9a3f88981ee67d9d5748f9e43eed1237422fb1