bcma: Kconfig: Let it depend on PCI

bcma also needs PCI, just like IOMEM and DMA, so let it depend on PCI,
or will cause building break for allmodconfig under c6x:

    CC [M]  drivers/bcma/driver_pcie2.o
  drivers/bcma/driver_pcie2.c: In function 'bcma_core_pcie2_up':
  drivers/bcma/driver_pcie2.c:196:8: error: implicit declaration of function 'pcie_set_readrq' [-Werror=implicit-function-declaration]
    err = pcie_set_readrq(dev, pcie2->reqsize);
          ^

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>