firmware: xilinx: Remove zynqmp_pm_get_eemi_ops() in IS_REACHABLE(CONFIG_ZYNQMP_FIRMWARE)

zynqmp_pm_get_eemi_ops() was removed in commit 4db8180f: "Firmware: xilinx:
Remove eemi ops for fpga related APIs", but not in IS_REACHABLE(CONFIG_ZYNQMP_FIRMWARE).
Any driver who want to communicate with PMC using EEMI APIs use the functions provided
for each function
This removed zynqmp_pm_get_eemi_ops() in IS_REACHABLE(CONFIG_ZYNQMP_FIRMWARE), and also
modify the documentation for this driver.

Fixes: 4db8180f ("firmware: xilinx: Remove eemi ops for fpga related APIs")
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Link: https://lore.kernel.org/r/20210215155849.2425846-1-iwamatsu@nigauri.org


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