memblock tests: update alloc_api to test memblock_alloc_raw

Update memblock_alloc() tests so that they test either memblock_alloc()
or memblock_alloc_raw() depending on the value of alloc_test_flags. Run
through all the existing tests in memblock_alloc_api twice: once for
memblock_alloc() and once for memblock_alloc_raw().

When the tests run memblock_alloc(), they test that the entire memory
region is zero. When the tests run memblock_alloc_raw(), they test that
the entire memory region is nonzero. The content of the memory region is
initialized to nonzero, and we expect it to remain unchanged if running
memblock_alloc_raw().

Reviewed-by: Shaoqin Huang <shaoqin.huang@intel.com>
Signed-off-by: Rebecca Mckeever <remckee0@gmail.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Link: https://lore.kernel.org/r/5a7cfb2f807ee2cb53ee77f9f5c910107b253d6e.1661578349.git.remckee0@gmail.com