bcma: fix build when CONFIG_OF_ADDRESS is not set

Commit 2101e533 ("bcma: register bcma as device tree driver")
introduces a hard dependency on OF_ADDRESS into the bcma driver.
OF_ADDRESS is specifically disabled for the sparc architecture.
This results in the following error when building sparc64:allmodconfig.

drivers/bcma/main.c: In function 'bcma_of_find_child_device':
drivers/bcma/main.c:150:3: error: implicit declaration of function 'of_translate_address'

Fixes: 2101e533

 ("bcma: register bcma as device tree driver")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>