soc: bcm: brcmstb: biuctrl: fix of_iomap leak

Smatch reports:

drivers/soc/bcm/brcmstb/biuctrl.c:291 setup_hifcpubiuctrl_regs() warn:
'cpubiuctrl_base' from of_iomap() not released on lines: 291.

This is because in setup_hifcpubiuctrl_regs(),
cpubiuctrl_base is not released when handle error, which may cause a leak.
To fix this, iounmap is added when handle error.

Fixes: 22f7a911 ("soc: brcmstb: Correct CPU_CREDIT_REG offset for Brahma-B53 CPUs")
Signed-off-by: Zhaoyang Li <lizhaoyang04@hust.edu.cn>
Reviewed-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
Link: https://lore.kernel.org/r/20230327115422.1536615-1-lizhaoyang04@hust.edu.cn


Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>