doc/README.fsl-clk was removed in commit
5b8e76c3 ("powerpc, 8xx: remove support for 8xx")
allthought CONFIG_SYS_FSL_CLK is defined in
arch/arm/cpu/armv8/fsl-layerscape/Kconfig and still in use
in the following configs:

./include/configs/mx53loco.h:21:#define CONFIG_SYS_FSL_CLK
./include/configs/m53evk.h:16:#define CONFIG_SYS_FSL_CLK
./include/configs/mx25pdk.h:17:#define CONFIG_SYS_FSL_CLK
./include/configs/usbarmory.h:14:#define CONFIG_SYS_FSL_CLK
./include/configs/ls1021aqds.h:14:#define CONFIG_SYS_FSL_CLK
./include/configs/mx53cx9020.h:22:#define CONFIG_SYS_FSL_CLK
./include/configs/colibri_vf.h:17:#define CONFIG_SYS_FSL_CLK
./include/configs/mx35pdk.h:21:#define CONFIG_SYS_FSL_CLK
./include/configs/woodburn_common.h:19:#define CONFIG_SYS_FSL_CLK
./include/configs/mx7_common.h:25:#define CONFIG_SYS_FSL_CLK
./include/configs/ls1021aiot.h:12:#define CONFIG_SYS_FSL_CLK
./include/configs/ls1021atwr.h:14:#define CONFIG_SYS_FSL_CLK
./include/configs/mx53ard.h:21:#define CONFIG_SYS_FSL_CLK
./include/configs/mx53smd.h:21:#define CONFIG_SYS_FSL_CLK
./include/configs/mx51evk.h:16:#define CONFIG_SYS_FSL_CLK
./include/configs/mx6_common.h:31:#define CONFIG_SYS_FSL_CLK
./include/configs/vf610twr.h:14:#define CONFIG_SYS_FSL_CLK
./include/configs/mx53evk.h:21:#define CONFIG_SYS_FSL_CLK

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Heiko Schocher <hs@denx.de>

There was for long time no activity in the 8xx area.
We need to go further and convert to Kconfig, but it
turned out, nobody is interested anymore in 8xx,
so remove it (with a heavy heart, knowing that I remove
here the root of U-Boot).

Signed-off-by: Heiko Schocher <hs@denx.de>

For most PPC platforms, they will call the first get_clocks() in
init_sequence_f[] as they define CONFIG_PPC. CONFIG_SYS_FSL_CLK is
then defined to call the second get_clocks(), which should be
redundant for PPC.

Signed-off-by: Gong Qianyu <Qianyu.Gong@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>