ARM: bcm: fix a leaked reference by adding missing of_node_put

ARM: bcm: fix a leaked reference by adding missing of_node_put

The call to of_get_next_child returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
usage.

Detected by coccinelle with the following warnings:
./arch/arm/mach-bcm/board_bcm281xx.c:43:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 35, but without a corresponding object release within this function.
./arch/arm/mach-bcm/platsmp-brcmstb.c:337:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 329, but without a corresponding object release within this function.
./arch/arm/mach-bcm/platsmp-brcmstb.c:341:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 329, but without a corresponding object release within this functio
./arch/arm/mach-bcm/bcm63xx_smp.c:150:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 130, but without a corresponding object release within this function.

Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Gregory Fong <gregory.0xf0@gmail.com>
Acked-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>