user_channel: user_mgmt: minor cleanup from cppcheck

[user_channel/user_mgmt.cpp:1628]: (style) The scope
of the variable 'usrEnabled' can be reduced.
[user_channel/user_mgmt.cpp:310]: (style) Unused variable: update

Tested: Not tested.
Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: Id38469ab5d5b0fa9c512f5a77fff1f1372e794c2
1 file changed