arm64/mm: Drop INIT_MM_CONTEXT()

Platform override for INIT_MM_CONTEXT() is redundant because swapper_pg_dir
always gets assigned as the pgd during init_mm initialization. So just drop
this override on arm64.

Originally this override was added via the 'commit 2b5548b6 ("arm64/mm:
Separate boot-time page tables from swapper_pg_dir")' because non standard
init_pg_dir was assigned as the pgd. Subsequently it was changed as default
swapper_pg_dir by the 'commit ba5b0333 ("arm64: mm: omit redundant
remap of kernel image")', which might have also just dropped this override.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20241202043553.29592-1-anshuman.khandual@arm.com


Signed-off-by: Will Deacon <will@kernel.org>