LinuxKPI: linux_pci.c: fix whitespace

Properly indent a line. No functional change.

Sponsored by: The FreeBSD Foundation
Approved by: re (cperciva)

(cherry picked from commit 68b1d162505149b8629f7e22cecf298cea2ff1f9)
(cherry picked from commit 069f504a8c4f9873ca32637cf0df1b0390b69b6a)