bcma: add missing includes

kbuild found out that commit 804e27de

 ("bcma: support bringing up
bus hosted on PCIe Gen 2") broke the build on m68k:

   drivers/bcma/driver_pcie2.c: In function 'bcma_core_pcie2_up':
>> drivers/bcma/driver_pcie2.c:196:2: error: implicit declaration of function 'pcie_set_readrq' [-Werror\
=implicit-function-declaration]
     err = pcie_set_readrq(dev, pcie2->reqsize);
     ^
   cc1: some warnings being treated as errors

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>