KVM: ppc: enable KVM_TRACE building for powerpc

This patch enables KVM_TRACE to build for PowerPC arch. This means just
adding sections to Kconfig and Makefile.

Signed-off-by: Jerone Young <jyoung5@us.ibm.com>
Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>