Change VA_BITS_MIN when we use 16K page.

Link: https://lkml.kernel.org/r/20240619074911.100434-6-kuan-ying.lee@canonical.com
Fixes: 9684ec18 ("arm64: Enable LPA2 at boot if supported by the system")
Signed-off-by: Kuan-Ying Lee <kuan-ying.lee@canonical.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>