gkdbus: Fix underflow and unreachable code bug

gkdbus: Fix underflow and unreachable code bug

Fix bugs that potentially cause underflow or unreachable code, so
update kdbus2.patch file.

Third input argument of g_array_remove_range() requires unsigned int type,
so negative value can cause underflow bug.

g_kdbus_msg_append_payload_vec() and g_kdbus_msg_append_payload_memfd() always
return TRUE, so add_body_vectors() return value is always TRUE.
In conclusion, error handler code for add_body_vectors() is useless, so remove it.

Change-Id: I1bbe9b60c5699db79a7821896397b3c2916087cc
Signed-off-by: Unsung Lee <unsung.lee@samsung.com>