cpupower: Bump soname version

Several functions in the libcpupower API are renamed or removed in
Linux 4.7.  This is an backward-incompatible ABI change, so the
library soname should change from libcpupower.so.0 to
libcpupower.so.1.

Fixes: ac5a181d ("cpupower: Add cpuidle parts into library")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>