powerpc/hv-24x7: Add rtas call in hv-24x7 driver to get processor details

For hv_24x7 socket/chip level events, specific chip-id to which
the data requested should be added as part of pmu events.
But number of chips/socket in the system details are not exposed.

Patch implements read_24x7_sys_info() to get system parameter values
like number of sockets, cores per chip and chips per socket. Rtas_call
with token "PROCESSOR_MODULE_INFO" is used to get these values.

Subsequent patch exports these values via sysfs.

Patch also make these parameters default to 1.

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200525104308.9814-3-kjain@linux.ibm.com