xilinx: zynqmp: Enable pmufw config reloading

PMU FW has functionality to accept and reload configuration object at run
time. The patch is adding support for doing it via u-boot prompt.

For example:
tftpboot 100000 pmu_obj.bin
zynqmp pmufw 100000 $filesize

The most of pmufw configurations don't allow config reloading.
Also official Xilinx PMUFW doens't support this feature properly but the
patch should open a way to call PMUFW with this request.

Here is example of PMUFW config fragment which enables config reloading.

/* SET CONFIG SECTION */
PM_CONFIG_SET_CONFIG_SECTION_ID,        /* Section ID */
PM_CONFIG_IPI_PSU_CORTEXA53_0_MASK | PM_CONFIG_IPI_PSU_CORTEXR5_0_MASK |
PM_CONFIG_IPI_PSU_CORTEXR5_1_MASK, /* Permissions to set config */

Signed-off-by: Michal Simek <michal.simek@xilinx.com>