DocBook/drm: can -> could

Signed-off-by: Michael Witten <mfwitten@gmail.com>

Documentation/DocBook/drm.tmpl

@@ -372,7 +372,7 @@
 	on the PCI device in the ROM BAR.  Note that after the ROM
 	has been mapped and any necessary information has been extracted,
 	it should be unmapped; on many devices, the ROM address decoder is
-	shared with other BARs, so leaving it mapped can cause
+	shared with other BARs, so leaving it mapped could cause
 	undesired behavior like hangs or memory corruption.
 <!--!Fdrivers/pci/rom.c pci_map_rom-->
       </para>