soc: brcmstb: Fix error path for unsupported CPUs

In case setup_hifcpubiuctrl_regs() returns an error, because of e.g:
an unsupported CPU type, just catch that error and return instead of
blindly continuing with the initialization. This fixes a NULL pointer
de-reference with the code continuing without having a proper array of
registers to use.

Fixes: 22f7a9116e ("soc: brcmstb: Correct CPU_CREDIT_REG offset for Brahma-B53 CPUs")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

drivers/soc/bcm/brcmstb/biuctrl.c

@@ -246,7 +246,9 @@ static int __init brcmstb_biuctrl_init(void)
 	if (!np)
 		return 0;
 
-	setup_hifcpubiuctrl_regs(np);
+	ret = setup_hifcpubiuctrl_regs(np);
+	if (ret)
+		return ret;
 
 	ret = mcp_write_pairing_set();
 	if (ret) {