Merge branch 'Rework-sparc32-page-table-layout'

Will Deacon says:

====================
Rework sparc32 page-table layout

This is a reposting of the patch series I sent previously to rework the
sparc32 page-table layout so that 'pmd_t' can be used safely with
READ_ONCE():

https://lore.kernel.org/lkml/20200324104005.11279-1-will@kernel.org

This is blocking the READ_ONCE() rework, which in turn allows us to
bump the minimum GCC version for building the kernel up to 4.8.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>