b43: Fix memory leaks in b43_bus_dev_ssb_init and b43_bus_dev_bcma_init

The memory allocated by kzalloc in b43_bus_dev_ssb_init and
b43_bus_dev_bcma_init is not freed.
This patch fixes the bug by adding kfree in b43_ssb_remove,
b43_bcma_remove and error handling code of b43_bcma_probe.

Thanks Michael for his suggestion.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Tested-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>