mtd/nand/r852: fix build for CONFIG_PCI disabled

mtd/nand/r852: fix build for CONFIG_PCI disabled

r852 fails to build when CONFIG_PCI is not enabled since it uses
pci_*() calls and is a PCI driver, so it should depend on PCI
to prevent build errors.
It should also #include <linux/pci.h>.

drivers/mtd/nand/r852.c:1053: error: implicit declaration of function 'pci_prepare_to_sleep'
drivers/mtd/nand/r852.c:1062: error: implicit declaration of function 'pci_back_from_sleep'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>