MIPS KVM trap & emulate mode (which is currently the only supported
mode) has to add an extra kseg0/kseg1 at 0x40000000 and an extra
kseg2/kseg3 at 0x60000000. Take this into account in
get_physical_address() so that debug memory access works.

This is done by translating the address to a standard kseg0 or kseg2
address before doing the normal address translation. The real virtual
address is still used for TLB lookups.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>