This converts the following to Kconfig:
CONFIG_SYS_FSL_CLK
We move the exiting option to common/Kconfig near the other options to
control the contents of board_init_f() and note that this is a legacy
option. We further restrict this to where the call is going to be
non-empty, for the SoCs that had only been using this for some
MMC-related clocks.
Signed-off-by: Tom Rini <trini@konsulko.com>