bcma: add Broadcom specific AMBA bus driver

Broadcom has released cards based on a new AMBA-based bus type. From a
programming point of view, this new bus type differs from AMBA and does
not use AMBA common registers. It also differs enough from SSB. We
decided that a new bus driver is needed to keep the code clean.

In its current form, the driver detects devices present on the bus and
registers them in the system. It allows registering BCMA drivers for
specified bus devices and provides them basic operations. The bus driver
itself includes two important bus managing drivers: ChipCommon core
driver and PCI(c) core driver. They are early used to allow correct
initialization.

Currently code is limited to supporting buses on PCI(e) devices, however
the driver is designed to be used also on other hosts. The host
abstraction layer is implemented and already used for PCI(e).

Support for PCI(e) hosts is working and seems to be stable (access to
80211 core was tested successfully on a few devices). We can still
optimize it by using some fixed windows, but this can be done later
without affecting any external code. Windows are just ranges in MMIO
used for accessing cores on the bus.

Cc: Greg KH <greg@kroah.com>
Cc: Michael Büsch <mb@bu3sch.de>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: George Kashperko <george@znau.edu.ua>
Cc: Arend van Spriel <arend@broadcom.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Botting <andy@andybotting.com>
Cc: linuxdriverproject <devel@linuxdriverproject.org>
Cc: linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>