ARM: prima2: fix incorrect panic usage

In prima2, some functions of checking DT is registered in initcall
level. If it doesn't match the compatible name of sirf, kernel
will panic. It blocks the usage of multiplatform on other verndor.

The error message is in below.

Knic - not syncing: unable to find compatible pwrc node in dtb
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-rc3-00006-gd7f26ea-dirty #86
[<c0013adc>] (unwind_backtrace+0x0/0xf8) from [<c0011430>] (show_stack+0x10/0x1)
[<c0011430>] (show_stack+0x10/0x14) from [<c026f724>] (panic+0x90/0x1e8)
[<c026f724>] (panic+0x90/0x1e8) from [<c03267fc>] (sirfsoc_of_pwrc_init+0x24/0x)
[<c03267fc>] (sirfsoc_of_pwrc_init+0x24/0x58) from [<c0320864>] (do_one_initcal)
[<c0320864>] (do_one_initcall+0x90/0x150) from [<c0320a20>] (kernel_init_freeab)
[<c0320a20>] (kernel_init_freeable+0xfc/0x1c4) from [<c026b9e8>] (kernel_init+0)
[<c026b9e8>] (kernel_init+0x8/0xe4) from [<c000e158>] (ret_from_fork+0x14/0x3c)
Signen-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/mach-prima2/pm.c

@@ -101,8 +101,10 @@ static int __init sirfsoc_of_pwrc_init(void)
 	struct device_node *np;
 
 	np = of_find_matching_node(NULL, pwrc_ids);
-	if (!np)
-		panic("unable to find compatible pwrc node in dtb\n");
+	if (!np) {
+		pr_err("unable to find compatible sirf pwrc node in dtb\n");
+		return -ENOENT;
+	}
 
 	/*
 	 * pwrc behind rtciobrg is not located in memory space

arch/arm/mach-prima2/rstc.c

@@ -28,8 +28,10 @@ static int __init sirfsoc_of_rstc_init(void)
 	struct device_node *np;
 
 	np = of_find_matching_node(NULL, rstc_ids);
-	if (!np)
-		panic("unable to find compatible rstc node in dtb\n");
+	if (!np) {
+		pr_err("unable to find compatible sirf rstc node in dtb\n");
+		return -ENOENT;
+	}
 
 	sirfsoc_rstc_base = of_iomap(np, 0);
 	if (!sirfsoc_rstc_base)