arm64/mm: Drop _PROT_SECT_DEFAULT

arm64/mm: Drop _PROT_SECT_DEFAULT

'commit db95ea787bd1 ("arm64: mm: Wire up TCR.DS bit to PTE shareability
fields")' dropped the last reference to symbol _PROT_SECT_DEFAULT, while
transitioning from PMD_SECT_S to PMD_MAYBE_SHARED for PROT_SECT_DEFAULT.
Hence let's just drop that symbol which is now unused.

Cc: Will Deacon <will@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20241021063713.750870-1-anshuman.khandual@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>