ARM: shmobile: koelsch: fix error return code check from clk_get()

The koelsch_add_standard_devices() function calls clk_get() but then fails
to check that it returns an error pointer instead of NULL on failure.

This was added by f31239ef ("ARM: shmobile: koelsch-reference:
Instantiate clkdevs for SCIF and CMT") in Simon Horman's
renesas-boards2-for-v3.14 tag.

The issue is not serious as it does not cause a crash and seems to not be
actually causing any issues now the other clock bugs have been fixed.
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[horms+renesas@verge.net.au: tweaked changelog]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/mach-shmobile/board-koelsch-reference.c

@@ -45,14 +45,14 @@ static void __init koelsch_add_standard_devices(void)
 
 	for (i = 0; i < ARRAY_SIZE(scif_names); ++i) {
 		clk = clk_get(NULL, scif_names[i]);
-		if (clk) {
+		if (!IS_ERR(clk)) {
 			clk_register_clkdev(clk, NULL, "sh-sci.%u", i);
 			clk_put(clk);
 		}
 	}
 
 	clk = clk_get(NULL, "cmt0");
-	if (clk) {
+	if (!IS_ERR(clk)) {
 		clk_register_clkdev(clk, NULL, "sh_cmt.0");
 		clk_put(clk);
 	}