sandbox: align LMB memory

sandbox: align LMB memory

To implement the EFI_SYSTEM_TABLE_POINTER we need 4 MiB aligned
memory.

On the sandbox LMB uses addresses relative to the start of a page aligned
RAM buffer allocated with mmap(). This leads to a mismatch of alignment
between EFI which uses pointers and LMB which uses phys_addr_t.

Ensure that the RAM buffer used for LMB is 4 MiB aligned.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>