bus: ti-sysc: Fix handling of invalid clocks

We can currently get "Unable to handle kernel paging request at
virtual address" for invalid clocks with dts node but no driver:

(__clk_get_hw) from [<c0138ebc>] (ti_sysc_find_one_clockdomain+0x18/0x34)
(ti_sysc_find_one_clockdomain) from [<c0138f0c>] (ti_sysc_clkdm_init+0x34/0xdc)
(ti_sysc_clkdm_init) from [<c0584660>] (sysc_probe+0xa50/0x10e8)
(sysc_probe) from [<c065c6ac>] (platform_drv_probe+0x58/0xa8)

Let's add IS_ERR checks to ti_sysc_clkdm_init() as And let's start treating
clk_get() with -ENOENT as a proper error. If the clock name is specified
in device tree we must succeed with clk_get() to continue. For modules with
no clock names specified in device tree we will just ignore the clocks.

Fixes: 2b2f7def ("bus: ti-sysc: Add support for missing clockdomain handling")
Acked-by: Roger Quadros <rogerq@ti.com>
Tested-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/pdata-quirks.c

@@ -491,11 +491,11 @@ static int ti_sysc_clkdm_init(struct device *dev,
 			      struct clk *fck, struct clk *ick,
 			      struct ti_sysc_cookie *cookie)
 {
-	if (fck)
+	if (!IS_ERR(fck))
 		cookie->clkdm = ti_sysc_find_one_clockdomain(fck);
 	if (cookie->clkdm)
 		return 0;
-	if (ick)
+	if (!IS_ERR(ick))
 		cookie->clkdm = ti_sysc_find_one_clockdomain(ick);
 	if (cookie->clkdm)
 		return 0;

drivers/bus/ti-sysc.c

@@ -280,9 +280,6 @@ static int sysc_get_one_clock(struct sysc *ddata, const char *name)
 
 	ddata->clocks[index] = devm_clk_get(ddata->dev, name);
 	if (IS_ERR(ddata->clocks[index])) {
-		if (PTR_ERR(ddata->clocks[index]) == -ENOENT)
-			return 0;
-
 		dev_err(ddata->dev, "clock get error for %s: %li\n",
 			name, PTR_ERR(ddata->clocks[index]));
 
@@ -357,7 +354,7 @@ static int sysc_get_clocks(struct sysc *ddata)
 			continue;
 
 		error = sysc_get_one_clock(ddata, name);
-		if (error && error != -ENOENT)
+		if (error)
 			return error;
 	}