eventdev: fix build on RHEL 7

eventdev: fix build on RHEL 7

Since queue identifier is passed as signed integer, a compilation error
is generated:
rte_event_eth_rx_adapter.c:1810:57: error: signed and unsigned type
in conditional expression [-Werror=sign-compare]
Make queue identifier as unsigned when adding it to vector data.

Bugzilla ID: 672
Fixes: d7c428e557ba ("eventdev: support Rx adapter event vector")

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
Acked-by: David Marchand <david.marchand@redhat.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>