configs: remove lpc32xx defconfigs

Those defconfigs rely on gcc 4.3.x, which was said to be the only gcc
version that was producing a working kernel. Since we have removed gcc
4.3.x, those defconfigs no longer build. Also, the kernel being used
in these defconfigs was 2.6.32, but there is a "new" 2.6.39 kernel
available from the lpclinux.com git repository, which maybe works fine
with more recent compilers.

However, those defconfigs were contributed by Alexandre Belloni, who
no longer has access to the hardware, so we have no way to verify that
a compiler update + kernel update actually works.

Therefore, we simply remove those defconfigs.

Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>