arch/frv/mb93090-mb00/pci-frv.c: fix build warning

arch/frv/mb93090-mb00/pci-frv.c: fix build warning

The build of frv defconfig gives warning:

  arch/frv/mb93090-mb00/pci-frv.c:176:5: warning: ignoring return value of 'pci_assign_resource', declared with attribute warn_unused_result

Just print an error message to silence the warning.  We can not do much
here on error.

Link: http://lkml.kernel.org/r/1484256471-5379-1-git-send-email-sudipm.mukherjee@gmail.com
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>