target/ppc/kvm: Add cap_ppc_safe_[cache/bounds_check/indirect_branch]

target/ppc/kvm: Add cap_ppc_safe_[cache/bounds_check/indirect_branch]

Add three new kvm capabilities used to represent the level of host support
for three corresponding workarounds.

Host support for each of the capabilities is queried through the
new ioctl KVM_PPC_GET_CPU_CHAR which returns four uint64 quantities. The
first two, character and behaviour, represent the available
characteristics of the cpu and the behaviour of the cpu respectively.
The second two, c_mask and b_mask, represent the mask of known bits for
the character and beheviour dwords respectively.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
[dwg: Correct some compile errors due to name change in final kernel
 patch version]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>