xl: move freemem()'s "credit expired" loop exit

xl: move freemem()'s "credit expired" loop exit

Move the "credit expired" loop exit to the middle of the loop,
immediately after "return true". This way having reached the goal on the
last iteration would be reported as success to the caller, rather than
as "timed out".

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>