Stellaris: Remove unused variables in LPC driver

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Stellaris/lpc: Use absolute address in fine-grained IO

Respect the convention that fine-grained IO operations take absolute
addresses. This eliminates the need to rely on two's complement
overflow when sending JEDEC commands, so remove this hack as well.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>