The were a couple long standing (since at least 2.4.21) superfluous 
variables and two unnecessary assignments in do_mlock().  The intent of 
the resulting code is also more obvious.

Tested on a 4 way x86 box running a simple mlock test program.  No 
problems detected.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>n