arm64: fix COMPAT_SHMLBA definition for large pages

arm64: fix COMPAT_SHMLBA definition for large pages

ARM glibc uses (4 * __getpagesize()) for SHMLBA, which is correct for
4KB pages and works fine for 64KB pages, but the kernel uses a hardcoded
16KB that is too small for 64KB page based kernels. This changes the
definition to what user space sees when using 64KB pages.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from commit b9b7aebb42d1b1392f3111de61136bb6cf3aae3f)
Signed-off-by: Alex Shi <alex.shi@linaro.org>