mm/hugetlb: suppress wrong warning info when alloc gigantic page

If hugetlb_cma is enabled, it will skip boot time allocation when
allocating gigantic page, that doesn't means allocation failure, so
suppress this warning info.

Link: https://lkml.kernel.org/r/20210219123909.13130-1-chenwandun@huawei.com
Fixes: cf11e85f

 ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>