c6x: remove unused COMMON_CLKDEV Kconfig parameter
This removes the COMMON_CLKDEV kernel configuration
parameter defined in arch/c6x/Kconfig, but used nowhere
in the makefiles and source code.
Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Signed-off-by: Mark Salter <msalter@redhat.com>