igb_uio: MSI IRQ mode
igb_uio: MSI IRQ mode

Add MSI to the list of possible IRQ modes.

Signed-off-by: Stephen Hemminger <06fa905d7f2aaced6dc72e9511c71a2a51e8aead@networkplumber.org>
[Thomas: isolate MSI code from other patch and don't set info.irq twice]
Acked-by: Thomas Monjalon <ee2fa8b2681c737f775687e475dcbf2028a412f1@6wind.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk