arm: dart6ul: fix ddr size macro

The previous macro was off by one bit and so we were getting a ddr
size which was twice the real size. This commit refactors the macro so
it returns the right size in _bytes_ and modifies the printf call so the
size is still printed in MiB.

Signed-off-by: Marc Ferland <ferlandm@amotus.ca>
1 file changed