sandbox: Change CONFIG_SANDBOX_BITS_PER_LONG to hard-coded

Instead of having CONFIG_SANDBOX_BITS_PER_LONG in sandbox.h set to 64
with a comment to change to 32 on a 32bit host, simply set this to 64 in
asm/types.h and have the comment be there.

Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>