vme8349.h contains two separate boards: The vme8349 itself, and the
caddy2 board. The caddy2 board is chosen by setting certain config
variables. Create a proper config file for the caddy2 board to make
Kconfig migration easier.

Furthermore, simplify the vme8349 and caddy2 configs by keeping only the
options necessary for each board.
Signed-off-by: NMario Six <mario.six@gdsys.cc>