mm/hugetlb: convert cmdline parameters from setup to early

mm/hugetlb: convert cmdline parameters from setup to early

Convert the cmdline parameters (hugepagesz, hugepages, default_hugepagesz
and hugetlb_free_vmemmap) to early parameters.

Since parse_early_param might run before MMU setups on some platforms
(powerpc), validation of huge page sizes as specified in command line
parameters would fail.  So instead, for the hstate-related values, just
record the them and parse them on demand, from hugetlb_bootmem_alloc.

The allocation of hugetlb bootmem pages is now done in
hugetlb_bootmem_alloc, which is called explicitly at the start of
mm_core_init().  core_initcall would be too late, as that happens with
memblock already torn down.

This change will allow earlier allocation and initialization of bootmem
hugetlb pages later on.

No functional change intended.

Link: https://lkml.kernel.org/r/20250228182928.2645936-8-fvdl@google.com
Signed-off-by: Frank van der Linden <fvdl@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin (Cruise) <roman.gushchin@linux.dev>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>