eal/linux: check interrupt file descriptor validity
eal/linux: check interrupt file descriptor validity

This patch fixes coverity issue by adding a check for negative event fd
value.

Coverity issue: 373711, 373694
Fixes: c2bd9367e18f ("lib: remove direct access to interrupt handle")

Signed-off-by: Harman Kalra <568a3484dfecf16d6b30cd214c570848bb408570@marvell.com>
Acked-by: David Marchand <f28529695cfa9e3e1eb84e7072aa626af4abb18e@redhat.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk