MIPS: Cavium: Add struct clocksource * argument to octeon_cvmcount_read()

This patch modifies parameter of octeon_cvmcount_read() from 'void' to
'struct clocksource *cs', which fixes compile warning for incompatible
parameter type.

Signed-off-by: Coly Li <coly.li@suse.de>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Ingo Molnar <mingo@elte.hu>
Reviewed-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>