arm: plat-omap: counter_32k: use IS_ERR() instead of NULL check

clk_get() returns ERR_PTR() on error, not NULL.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
[tony@atomide.com: updated to include err.h to compile on omap1]
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/counter_32k.c

@@ -16,6 +16,7 @@
 #include <linux/init.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/err.h>
 
 #include <plat/common.h>
 #include <plat/board.h>
@@ -164,7 +165,7 @@ static int __init omap_init_clocksource_32k(void)
 			return -ENODEV;
 
 		sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
-		if (sync_32k_ick)
+		if (!IS_ERR(sync_32k_ick))
 			clk_enable(sync_32k_ick);
 
 		clocksource_32k.mult = clocksource_hz2mult(32768,