firmware: xilinx: Fix incorrect names in kernel-doc

firmware: xilinx: Fix incorrect names in kernel-doc

There are some c&p issues reported by kernel-doc as:
drivers/firmware/xilinx/zynqmp.c:676: warning: expecting prototype for
zynqmp_pm_write_ggs(). Prototype was for zynqmp_pm_read_ggs() instead
drivers/firmware/xilinx/zynqmp.c:710: warning: expecting prototype for
zynqmp_pm_write_pggs(). Prototype was for zynqmp_pm_read_pggs() instead
drivers/firmware/xilinx/zynqmp.c:1023: warning: expecting prototype for
zynqmp_pm_aes(). Prototype was for zynqmp_pm_aes_engine() instead

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/a81edd4fc6cff4bd7e4984fceda941b9e9ab01bf.1628245954.git.michal.simek@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>