MAINTAINERS: update HUGETLB reviewers

I have done quite some review on hugetlb code over the years, and some
work on it as well, the latest being the hugetlb pagewalk unification
which is a work in progress, and touches hugetlb code to great lengths.

HugeTLB does not have many reviewers, so I would like to help out by
offering myself as an official Reviewer.

Signed-off-by: Oscar Salvador <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Acked-by: David Hildenbrand <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Muchun Song <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Peter Xu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: osalvadorvilardaga

MAINTAINERS

@@ -10954,6 +10954,7 @@ F:	include/linux/platform_data/huawei-gaokun-ec.h
 
 HUGETLB SUBSYSTEM
 M:	Muchun Song <[email protected]>
+R:	Oscar Salvador <[email protected]>
 L:	[email protected]
 S:	Maintained
 F:	Documentation/ABI/testing/sysfs-kernel-mm-hugepages