ARM: OMAP: Remove unnecessary clk structure

In the plat/dmtimer.h there is a structure named "clk" declared. This structure
is not used and appears to be left over from previous code. Hence, remove this
unused structure.

Verified that both omap1 and omap2plus kernel configurations build with this
change.
Signed-off-by: NJon Hunter <jon-hunter@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>

arch/arm/plat-omap/include/plat/dmtimer.h

@@ -71,7 +71,6 @@ struct omap_timer_capability_dev_attr {
 };
 
 struct omap_dm_timer;
-struct clk;
 
 struct timer_regs {
 	u32 tidr;