[PATCH] umem: check pci_set_dma_mask return value correctly

Signed-off-by: Tobias Klauser <tklauser@nuerscht.ch>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>