openrisc: time: don't mark comment as kernel-doc

Fix a kernel-doc warning by unmarking the comment as being in
kernel-doc notation.

Fixes this warning:
arch/openrisc/kernel/time.c:137: warning: expecting prototype for Clocksource(). Prototype was for openrisc_timer_read() instead

Fixes: b731fbbd ("OpenRISC: Timekeeping")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: openrisc@lists.librecores.org
Signed-off-by: Stafford Horne <shorne@gmail.com>