rapidio/tsi721: Fix interrupt mask when handling MSI

rapidio/tsi721: Fix interrupt mask when handling MSI

Commit 1619f441963e 'rapidio/tsi721: fix bug in MSI interrupt
handling' (commit 1ccc819da6fd upstream) makes the MSI handler disable
and re-enable interrupts.  When re-enabling interrupts, we should set
the same flags as were originally set, but this changed in Linux 3.5 so
the flags are now inconsistent in 3.2.  In fact, the extra flag isn't
even defined in 3.2.  Remove the extra flag from the MSI handler.

Reported-by: Steve Conklin <steve.conklin@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>