MIPS: Adjust set_pte() SMP fix to handle R10000_LLSC_WAR

MIPS: Adjust set_pte() SMP fix to handle R10000_LLSC_WAR

commit 128639395b2ceacc6a56a0141d0261012bfe04d3 upstream.

Update the recent changes to set_pte() that were added in 46011e6ea392
to handle R10000_LLSC_WAR, and format the assembly to match other areas
of the MIPS tree using the same WAR.

This also incorporates a patch recently sent in my Markos Chandras,
"Remove local LL/SC preprocessor variants", so that patch doesn't need
to be applied if this one is accepted.

Signed-off-by: Joshua Kinard <kumba@gentoo.org>
Fixes: 46011e6ea392 ("MIPS: Make set_pte() SMP safe.)
Cc: David Daney <david.daney@cavium.com>
Cc: Linux/MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/11103/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[bwh: Backported to 3.2:
 - Use {LL,SC}_INSN not __{LL,SC}
 - Use literal arch=r4000 instead of MIPS_ISA_ARCH_LEVEL since R6 is not
   supported]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>