MIPS: tlbex: Clear ISA bit when writing to handle_tlb{l,m,s}

MIPS: tlbex: Clear ISA bit when writing to handle_tlb{l,m,s}

When generating TLB exception handling code we write to memory reserved
at the handle_tlbl, handle_tlbm & handle_tlbs symbols. Up until now the
ISA bit has always been clear simply because the assembly code reserving
the space for those functions places no instructions in them. In
preparation for marking all LEAF functions as containing code,
explicitly clear the ISA bit when calculating the addresses at which to
write TLB exception handling code.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14507/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>