Bluetooth: RFCOMM: Pass session instead of dlc in make_uih_msg()

rfcomm_make_uih_msg() only needs session to get the role while creating
msg. This is mainly done since some commands like Test and RPN may come
even before dlc is created.

Change-Id: Ifd5a2ceaf17c20db3f00604cd2b4f1759155123e
Signed-off-by: Jaganath Kanakkassery <jaganathx.kanakkassery@intel.com>