flash: remove lpc2000 clang warnings

By Initialising the param_table we remove the clang warning's.
We are also make sure we are not passing any rogue values to lpc2000_iap_call.

Change-Id: Idb3b0077d1dae5f03dedab1d46d01140fe9ffb10
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/777


Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>