PCI: endpoint: Select CRC32 to fix test build error

The PCI endpoint test driver uses crc32_le() so it should select
CRC32.  Fixes this build error (when CRC32=m):

  drivers/built-in.o: In function `pci_epf_test_cmd_handler':
  pci-epf-test.c:(.text+0x2d98d): undefined reference to `crc32_le'

Fixes: 349e7a85 ("PCI: endpoint: functions: Add an EP function to test PCI")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>