Docs: MSI-HOWTO: Insert `that'

... as per Randy Dunlap's wishes :-P
Message-Id: <20110717114023.2b4cce91.rdunlap@xenotime.net>

Signed-off-by: Michael Witten <mfwitten@gmail.com>
Acked-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>

Documentation/PCI/MSI-HOWTO.txt

@@ -190,7 +190,7 @@ during the initialization phase.
 
 It is ideal if drivers can cope with a variable number of MSI-X interrupts,
 there are many reasons why the platform may not be able to provide the
-exact number a driver asks for.
+exact number that a driver asks for.
 
 A request loop to achieve that might look like: