irdma(4): Fix compile error on powerpc64

Jenkins reports that the type used in a printf() specifier is
incorrect, so fix it in order to use the appropriate type.

Signed-off-by: Eric Joyner <erj@FreeBSD.org>

Reported by: Jenkins CI
MFC after: 6 days
MFC-with: cdcd52d41e246ba1c0fcfad0769bd691487355ef
Sponsored by: Intel Corporation