powerpc/pseries: Add ibm,get-dynamic-sensor-state RTAS call support

powerpc/pseries: Add ibm,get-dynamic-sensor-state RTAS call support

The RTAS call ibm,get-dynamic-sensor-state is used to get the
sensor state identified by the location code and the sensor
token. The librtas library provides an API
rtas_get_dynamic_sensor() which uses /dev/mem access for work
area allocation but is restricted under system lockdown.

This patch provides an interface with new ioctl
 PAPR_DYNAMIC_SENSOR_IOC_GET to the papr-indices character
driver which executes this HCALL and copies the sensor state
in the user specified ioctl buffer.

Refer PAPR 7.3.19 ibm,get-dynamic-sensor-state for more
information on this RTAS call.
- User input parameters to the RTAS call: location code string
  and the sensor token

Expose these interfaces to user space with a /dev/papr-indices
character device using the following programming model:
 int fd = open("/dev/papr-indices", O_RDWR);
 int ret = ioctl(fd, PAPR_DYNAMIC_SENSOR_IOC_GET,
		struct papr_indices_io_block)
  - The user space specifies input parameters in
    papr_indices_io_block struct
  - Returned state for the specified sensor is copied to
    papr_indices_io_block.dynamic_param.state

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Tested-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250416225743.596462-6-haren@linux.ibm.com